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A new genus and species of rhinatrematid caecilian, Amazops amazops gen. et sp. nov., is described based on a single specimen from Orellana, Ecuador collected in 1990. Among other features the new taxon differs from all other rhinatrematid caecilians in having less than four annular grooves interrupted in the region of the vent and in the squamosal contributing to the bony margin of the orbit. A consideration of its distinctive morphology suggests that it is plausible that the new taxon is the sister taxon of all other rhinatrematid caecilians. That the genus is known from a single specimen, and that this is the first new rhinatrematid species from the Andes described for more than 50 years, highlights the poor sampling (collecting) of rhinatrematid caecilians and limited knowledge of their diversity.

Information on even the most basic biological aspects is often missing for many species and even higher taxa of caecilians. As in other amphibians, development is plesiomorphically biphasic and aquatic larvae are present in Rhinatrematidae, Ichthyophiidae, and some Indotyphlidae. However, only very little information on larval morphology and ecology is available. Here I describe a series of Epicrionops bicolor larvae and metamorphs from Peru and provide details on the development of the annulation pattern, colouration, external gills, lateral line system, and other morphological characters and discuss the taxonomic value of lateral line characters. Specimens were collected at two different times of the year, allowing inferences of a few key demographic characteristics. Hatching probably occurs around August and September at a size of approximately 55 to 65 mm. Larval development takes about 1 year to complete and metamorphosis occurs at around 180–190 mm total length.

Amazops gen. nov. {urn:lsid:zoobank.org:act:D9F1C39D-4B47-46CF-AB9D-51896D4C619C} Diagnosis. Rhinatrematid caecilians with the squamosal contributing to the margin of the orbit. Content: A single species Amazops amazops, sp. nov., the type by monotypy and by designation. Etymology: The name is a portmanteau word combining reference to the Amazonian provenance of the type and only known species and the distinctive topological relationships of its eye and orbit, particularly the contribution of the squamosal to the bony margin of the orbit, which is unknown in any other rhinatrematid. As mandated by the code, gender is masculine. Remarks: Three other features of the only known specimen of this genus are distinctive, known in no other rhinatrematids and might be diagnostic for the genus:lack of contact between the quadrate and maxillopalatine, contact between the squamosal and frontal and the small number of annular grooves that are interrupted by the vent., Published as part of Wilkinson, Mark, Reynolds, Robert P. & Jacobs, Jeremy F., 2021, A new genus and species of rhinatrematid caecilian (Amphibia: Gymnophiona: Rhinatrematidae) from Ecuador, pp. 27-34 in Herpetological Journal 31 (1) on page 28, DOI: 10.33256/31.1.2734, http://zenodo.org/record/5838883

Caecilians (order Gymnophiona) are elongate, limbless, snake-like amphibians that are the sister-group (closest relatives) of all other recent amphibians (frogs and salamanders). Little is known of their cardiovascular anatomy and physiology, but one nearly century old study suggests that Hypogeophis (family Indotyphlidae), commonly relied upon as a representative caecilian species, has atrial septation in the frontal plane and more than one septum. In contrast, in other vertebrates there generally is one atrial septum in the sagittal plane. We studied the adult heart of Idiocranium (also Indotyphlidae) using immunohistochemistry and confirm that the interatrial septum is close to the frontal plane. Additionally, a parallel right atrial septum divides three-fourths of the right atrial cavity of this species. Idiocranium embryos in the Hill collection reveal that atrial septation initiates in the sagittal plane as in other tetrapods. Late developmental stages, however, see a left-ward shift of visceral organs and a concordant rotation of the atria that reorients the atrial septa towards the frontal plane. The gross anatomies of species from six other caecilian families reveal that (i) the right atrial septum developed early in caecilian evolution (only absent in Rhinatrematidae) and that (ii) rotation of the atria evolved later and its degree varies between families. In most vertebrates a prominent atrial trabeculation associates with the sinuatrial valve, the so-called septum spurium, and the right atrial septum seems homologous to this trabeculation but much more developed. The right atrial septum does not appear to be a consequence of body elongation because it is absent in some caecilians and in snakes. The interatrial septum of caecilians shares multiple characters with the atrial septum of lungfishes, salamanders and the embryonic septum primum of amniotes. In conclusion, atrial septation in caecilians is based on evolutionarily conserved structures but possibly exhibits greater variation than in any other vertebrate order.

Epicrionops parkeri (Dunn, 1942): Figure 7C Rhinatrema parkeri Dunn 1942: 458. Epicrionops parkeri — Taylor 1968: 216. Material examined. Table 1. A bicolored caecilian with well-developed tail; lateral stripe yellow, cream or white from head or second collar onto tail; stripe ending at posterior level of vent; subcaudal region dark lilac to blackish (Taylor 1968). Epicrionops parkeri differs from E. bicolor (a species with similar coloration pattern distributed in Colombia) by having a larger body length and 198 primary annuli (in contrast to 117–135 primary annuli in E. bicolor)., Published as part of Restrepo, Adriana, Molina-Zuluaga, Claudia, Hurtado, Juan P., Marín, Carlos M. & Daza, Juan M., 2017, Amphibians and reptiles from two localities in the northern Andes of Colombia, pp. 203-237 in Check List 13 (4) on page 217, DOI: 10.15560/13.4.203, {"references":["Dunn ER (1942) The American caecilians. Bulletin of the Museum of Comparative Zoology, Harvard University 91: 439 - 540.","Taylor EH (1968) The Caecilians of the World: A Taxonomic Review. University of Kansas Press, Lawrence, 848 pp."]}

The reduction in the visual system of the Gymnophiona has been noted by many authors. Adult caecilian amphibians eyes are small, covered by skin and sometimes bone, with retinal cells that contain only rod opsins and co-option of structures usually associated with the visual system used for novel sensory structures and functions. Here, we provide a description of the eye of Rhinatrema bivittatum, the first of any rhinatrematid caecilian, and consider its significance for our understanding of the nature of the eye in the last common ancestor of living caecilians. Characters discovered include zonule fibres, an aqueous humour and the remnants of an attachment that could be a protractor lentis muscle.

Caecilians are wormlike amphibians that occur worldwide in the tropics, except for Madagascar and Oceania. Only 189 species are known, distributed among 35 genera and 10 families. Most caecilians are fossorial, living in moist soils usually adjacent to streams, lakes, and swamps; a few species are aquatic. Conservation status of caecilians is summarized. An up-to-date phylogeny details approximate time periods during which divergences occurred during the evolutionary history of caecilians and shows evolutionary relationships among the families as we now know them. Taxonomic accounts provide information on generic content, distribution, characteristics, and biology of each family.

The morphology of the tectum mesencephali and the medial pallium is studied in species representing the six families of caecilians (Amphibia: Gymnophiona) in order to determine whether differences in brain morphology are related to function, phylogenetic history, or life history strategies. In general, the caecilian tectum is characterized by simplification in having little to no lamination and few migrated cells. The degree of morphological complexity differs between species and between brain regions. Our data suggest that changes in brain morphology are due to a mosaic of different influences. We did not find a strict correlation between visual system reduction and tectal morphologies. However, phylogenetic effects exist. The greatest degree of morphological complexity is found in members of the Rhinatrematidae, a family that is considered basal to the lineage. Thus, simplification of brain morphology in caecilians must be considered a secondary or derived rather than a primitive feature. Direct development and miniaturization are correlated with the greatest simplification in the tectum mesencephali and medial pallium. There is a relationship between differences in brain morphology and heterochrony in caecilians, as in other amphibians. J. Morphol. 231:11-27, 1997. © 1997 Wiley-Liss, Inc.

Previous studies have shown there to be considerable inter-specific variation in the cardiovascular anatomy of five of the six families of caecilians. Observations on the previously unstudied Rhinatrematidae reveal this family to be characterized by a number of cardiovascular features that are unique within the Gymnophiona. These include a poorly developed sinus venosus sinistra, a short truncus arteriosus, separate carotid and systemic arches and the right atrium larger than the left. Character analysis indicates that these unique features are primitive within the Gymnophiona and they provide considerable additional support for the hypothesis that the Rhinatrematidae are the sister-group to all other caecilians. This hypothesis appears to be among the best supported hypotheses of relationships within the Gymnophiona. Caecilian cardiovascular variation provides a useful source of evidence for phylogeny reconstruction that should be integrated into phylogenetic studies of the group.

Maddin, Hillary C., Russell, Anthony P., Anderson, Jason S. (2012): Phylogenetic implications of the morphology of the braincase of caecilian amphibians (Gymnophiona). Zoological Journal of the Linnean Society 166 (5): 160-201, DOI: 10.1111/j.1096-3642.2012.00838.x, URL: http://dx.doi.org/10.1111/j.1096-3642.2012.00838.x

RHINATREMATIDAE Nussbaum, 1977 Rhinatrema Dum��ril & Bibron, 1841 Diagnosis. Specimens with maximum known TL 353 mm. Tentacular aperture in a longitudinal, semicircular slit in skin, projecting anteriorly from anterior edge of eye. Nostrils subcircular, visible from above, near tip of snout. Vent longitudinal, transverse or T-shaped. True tail present, with maximally 11 annuli. In males, ventral tail tubercles present or not. Mouth terminal; snout not projecting beyond mouth. Tongue may have longitudinal grooves or not; completely attached to mandibular mucosa. No narial plugs. Palatal mucosa smooth. Four tooth series. One row of scales per body fold. Boldly patterned brown with yellow longitudinal lateral bands. Two species in Amazonian Brazil., Published as part of Maciel, Adriano O. & Hoogmoed, Marinus S., 2011, Taxonomy and distribution of caecilian amphibians (Gymnophiona) of Brazilian Amazonia, with a key to their identification, pp. 1-53 in Zootaxa 2984 on page 41, DOI: 10.5281/zenodo.203509, {"references":["Nussbaum, R. A. (1977) Rhinatrematidae: A new family of caecilians (Amphibia: Gymnophiona). Occasional Papers of the Museum of Zoology, University of Michigan 682, 1 - 30."]}

Rhinatrema ron Wilkinson & Gower, 2010 Diagnosis. Maximum known TL 353 mm. A Rhinatrema without large cephalic spot on anterior part of head, TBA 276���347. No tail tubercles in males or females. Vent may be transverse or longitudinal. Only first nuchal groove clearly distinct. Tongue with distinct longitudinal grooves. Palatal mucosa distinctly plicate. Rhinatrema ron differs from R. bivittatum mainly in having a plicate palatal mucosa; lacking a large yellow spot on the anterior region of head; lacking pale spots on dorsal and ventral surfaces of the tail; in the absence of tail tubercles in males and in having only first nuchal groove distinct. Rhinatrema ron differs from R. shiv Gower et al., 2010 in having a lower number of TBA (276���347 instead of 335���382 in R. shiv). Description. TL 19.6���27.7 times (24.3 �� 4.7; n = 33) BW. Nostrils subcircular, visible from above, near tip of snout. Eyes visible in open orbit; medially positioned between nostrils and corner of mouth, slightly closer to nostrils than corner of mouth in most specimens. Eyes at same level as, or slightly above, nostrils. Palatal mucosa plicate. First nuchal groove distinct dorsally and ventrally, no dorsal transverse groove; second and third nuchal grooves indistinct. Body subcylindrical, slightly wider than deep. Most annular grooves complete, except some anterior grooves which are ventrally incomplete (e.g. four in MPEG 19966), and grooves interrupted by the vent. Small terminal shield on tip of tail. Tail small and slender, maximum length 3.5 mm (MPEG 26477). All tail annuli complete in males and females; no tubercles on ventral region of tail in either sex. Dermal scales from first body annulus to last tail annulus; one row of dermal scales per body annulus, completely encircling the body, except in first few incomplete body annuli. The vent may be transverse or longitudinal (Fig. 22); AD 13���20 (15.4 �� 5.4; n = 29). Paired anal papillae may be present; found in 14 of 22 males and two of 10 females specimens assessed. PMT maximally 30 with slight variation in size, maxillary teeth slightly larger, they may extend posteriorly of choanae, as PPT. PPT maximally 40, with little variation in size. No diastema between PVT and PT; teeth smaller than those in maxillary series DT maximally 26, approximately same size as PMT. ST maximally 22, approximately same size as PPT. Color. Two color patterns for the dorsum of the body can be discerned (Fig. 24). In the first, the dorsal region is predominantly dark brown with sparse yellow spots. The other pattern is characterized by more and closer spaced yellow spots than in the first pattern. The holotype (MZUSP 60016; Wilkinson & Gower, 2010) has the second pattern. Border of lower jaw, as well as dorsal and lateral surface of head above the commissure of the mouth differ from dorsal body color pattern in having yellow spots of larger size. A specimen from Urucar�� municipality (MPEG 26945) and the holotype from Manaus, state of Amazonas, Brazil have a more yellowish head than specimens from Oriximin��, state of Par��, Brazil. Yellow stripe with dorsal and ventral border not well defined on sides of body from nuchal region to level of vent; it may extend anteriorly to corner of mouth. Ventral surface of body paler than dorsum, with fewer yellow spots. In preservative, yellowish body parts become whitish or pale yellow, and brownish parts become bluish in some specimens. See photos of live specimens (Fig. 24) and those of the preserved holotype in Wilkinson & Gower, 2010. Variation. There is no sexual variation in color. Females have higher means in most of the morphometric characters studied. Given the rather small number of specimens, we did not apply ANOVA to test sexual dimorphism and only present the differences in Table 14. Distribution. Known from the type locality, approximately 70 km north of Manaus, and in the municipality of Urucar, state of Amazonas north of the Amazon, Brazil. Also in the southern and northern parts of the municipality of Oriximin, state of Par, Brazil (Fig. 23). A rhinatrematid larva from Parque Nacional Montanhas do Tumucumaque, Amap state, Brazil is present in the material of IEPA (IEPA /TQ 634). The specimen has a longitudinal vent and because of this might belong to R. ron, but because hardly anything is known about the ontogeny of Rhinatrema, we prefer not to include this specimen in the treatment of this species or the distribution map. This specimen has no annuli in the anteriormost part of the body, which might be a larval character. The specimen hails from an area (Tumuc Humac) from which only R. bivittatum is known, but because of the longitudinal vent we prefer to mention this specimen here. Natural history. According to field notes of D��lio Ba��ta and of Emiliane G. Pereira, most specimens were collected in pitfall traps. MPEG 26477 was collected at 22.55 h on the ground in rainforest (M.A. Ribeiro-Junior, pers. comm.). These data are consistent nocturnal foraging on the surface of the soil., Published as part of Maciel, Adriano O. & Hoogmoed, Marinus S., 2011, Taxonomy and distribution of caecilian amphibians (Gymnophiona) of Brazilian Amazonia, with a key to their identification, pp. 1-53 in Zootaxa 2984 on pages 44-46, DOI: 10.5281/zenodo.203509

Based on examination of 622 specimens of Gymnophiona, 15 species are recognized for Brazilian Amazonia. Geographical variation in characters is low and is mainly restricted to the number of annuli. One new species is described, Microcaecilia rochai sp. nov. New distribution data and maps for most species are provided. A key to the identification of caecilians of Brazilian Amazonia is presented.

Rhinatrema bivittatum (Gu��rin-M��neville, 1838) Caecilia bivittatum Gu��rin-M��neville, 1838: 16. Rhinatrema bivittatum: Dum��ril & Bibron, 1841: 288; Taylor, 1968: 159; Hoogmoed, 1979: 273; Frost, 1985: 637; Lescure & Marty, 2000: 294; Gaucher et al., 2004; Frost, 2008; Stuart et al., 2008: 95. Diagnosis. Maximum known TL 246 mm. Rhinatrema with a large yellow cephalic spot; total body annuli 315��� 384. Males may have granules on ventral surface of tail, posterior of vent. Ventrally complete annular grooves posterior of vent only in females. Longitudinal grooves may be present on the tongue or not. First and second nuchal grooves distinct, third nuchal groove not readily distinct from annular and collar grooves. Description. TL 22.2���31.4 times (26.6 �� 2.6; n = 10) BW. Nostrils subcircular, visible from above, near tip of snout. Eyes visible in open orbit; positioned midway between nostrils and corner of mouth, slightly closer to nostrils than corner of mouth in most specimens. Eyes at same level as or slightly above nostrils. First nuchal groove distinct dorsally; second complete dorsally and ventrally; third groove indistinct; no dorsal transverse groove on first collar. Body subcylindrical, slightly wider than deep. Most annular grooves complete, except some anterior grooves which are ventrally incomplete (e.g. six in MPEG 23548), and grooves interrupted by vent (e.g. five in MPEG 23549). Small terminal shield. Tail small and slender. Sexual dimorphism in structure of tail: all tail annular grooves are incomplete in males, due to presence of tubercles on ventral surface of tail; females without ventral tubercles but with complete and some (e.g. four in MPEG 23548) incomplete annuli. Dermal scales from first body annulus to last annulus on tail; one row of dermal scales per body fold, rows completely encircling body, except in first incomplete body annulus and in incomplete tail annuli. Vent transverse or T-shaped (Fig. 22); AD 10���12 (11 �� 5; n = 7). Paired anal papillae present or not; found in one of five males and absent in five analyzed females. According to Taylor (1968), tongue strongly marked by grooves but in specimens studied here longitudinal grooves are absent or only slightly distinct on surface of tongue. PMT maximally 28 with variation in size, maxillary teeth slightly larger, they may extend posteriorly of level of choanae as PPT. PPT maximally 28, with hardly any variation in size; smaller than maxillary teeth. DT maximally 25, approximately same size as PMT. ST at most 28, approximately same size as PPT. Color. Tip of snout yellow; irregular, large yellow spot on anterior region of head, generally not reaching tip of snout, posteriorly surpassing level of eyes, but not reaching occipital region. Irregular yellow stripe connecting eyes and nostrils. Upper and lower border of mouth same yellow as cephalic spot, and those two stripes may fuse into one stripe on side of head behind corner of mouth. Gular region same color as venter; yellow stripe with irregular upper and lower border on sides of body from level of collars to level of vent; can be fused to mouth stripes. Dorsum of body brown with small yellow spots randomly distributed; underside slightly paler than dorsum and with more dispersed yellow spots. A yellow spot may be present on dorsal part of tail (e.g. MPEG 26941 and IEPA / TQ 287) or be absent (e.g. MPEG 23549, IEPA /TQ 306, IEPA /TQ 348, IEPA /TQ 272). Females with small paler region close to tip of tail. Tongue dark. Variation. Males may have a group of tubercles on ventral region of tail (Fig. 22); absent in females. No apparent sexual difference in number of annuli as suggested by Nussbaum & Hoogmoed (1979). Further data on variation in description and in Table 14. Rhinatrema ron Rhinatrema bivittatum Rhinatrema ron Rhinatrema bivittatum Male Female Male Female Distribution. Guyana, French Guiana, Suriname and Brazil (states of Amap�� and Par�� north of the Amazon) (Fig. 23). Remarks. Nussbaum & Hoogmoed (1979) examined only four specimens of R. bivittatum: the holotype from Cayenne, French Guiana, and three specimens collected in Brazil, Guyana and Suriname. Recent collections in French Guiana (Lescure & Marty, 2000; Wilkinson & Nussbaum, 2006) and in Brazil show that this species is not uncommon. Taylor (1968) noted that the second collar is distinct and larger than first, but did not mention the third nuchal groove. He considered the first few ventrally incomplete body annuli as the posterior limit of the second collar in both R. bivittatum and Epicrionops spp. (Taylor 1968). Here we regard the third nuchal groove as indistinct and consequently also the posterior delimitation of the second collar. Gower et al. (2010) and Wilkinson & Gower (2010) identified the third nuchal groove in Rhinattrema as the anteriormost groove behind the second nuchal groove that wraps around beyond the stripe and on to the ventral surface. Gower et al. (2010) presented data on variation in mostly French Guiana specimens of R. bivittatum. They noted that all specimens they examined had a yellow spot on the dorsal surface of the body terminus. Gower et al. (2010) and Wilkinson & Gower (2010) mentioned that the only Rhinatrema specimen (RMNH 17667) known from Suriname possibly represents a species different from R. bivittatum, R. shiv and R. ron by having a longer tail and a higher number of tail annuli., Published as part of Maciel, Adriano O. & Hoogmoed, Marinus S., 2011, Taxonomy and distribution of caecilian amphibians (Gymnophiona) of Brazilian Amazonia, with a key to their identification, pp. 1-53 in Zootaxa 2984 on pages 42-44, DOI: 10.5281/zenodo.203509, {"references":["Taylor, E. H. (1968). The Caecilians of the World. A taxonomic review. University of Kansas Press. Lawrence, Kansas. 848 pp.","Frost, D. R. (Ed.) (1985) Amphibian species of the world. A taxonomic and geographic reference. Allen Press. Inc., and Assoc. Systematics Collections, Lawrence, Kansas. 732 pp.","Lescure, J., & Marty, C. (2000) Atlas des Amphibiens de Guyane. Patrimoine nationale 45, 1 - 388.","Frost, D. R. (2008) Amphibian Species of the World: an Online Reference. Version 5.2 American Museum of Natural History, New York, USA. Available from: http: // research. amnh. org / herpetology / amphibia / index. php. (Accessed 0 8 January 2009).","Stuart, S., Hoffmann, M., Chanson, J., Cox, N., Berridge, R., Ramani, P. & Young, B. (eds.), 2008. Threatened Amphibians of the World. 758 pp. Lynx Editions, Barcelona.","Nussbaum, R. A. & Hoogmoed, M. S. (1979) Surinam caecilians, with notes on Rhinatrema bivittatum and the description of a new species of Microcaecilia (Amphibia, Gymnophiona). Zoologische Mededelingen, Leiden, 54, 217 - 235.","Wilkinson, M. & Nussbaum, R. A. (2006) Caecilian phylogeny and classification. In: Exbrayat, J. M. (Ed.), Reproductive Biology and phylogeny of Gymnophiona (caecilians). Science Publisher Inc., Enfield, pp. 39 - 78."]}

Rhinatrema ron sp. nov. (Figs. 1���2; Table 1) Holotype. MZUSP 60016, a mature female, from Reserva INPA-WWF km 76 BR- 174, Amazonas, Brazil. Collected by B. Zimmerman, 10 April, 1983. Diagnosis. A Rhinatrema that differs from its congeners, R. bivittatum (Gu��rin-M��neville, 1838) and R. shiv Gower, Wilkinson, Sherratt & Kok, 2010, in having a strongly plicate tongue and palatal mucosa, a more strongly mottled/flecked colour pattern with larger pale patches, a thicker lateral stripe, eyes that are much further from the lip than are the nares, and a much larger maximum body size (> 300 mm). Description of holotype. Some morphometric and meristic data are given in Table 1. Good condition except c. 30 mm midventral longitudinal incision c. 75 mm anterior to terminus, some open scale pockets, a possibly artefactually slightly flattened snout tip, narrow constriction caused by tag string c. 42 mm behind snout tip. Body subcylindrical, dorsoventrally compressed, fairly uniform, L/W = 26.3, tapering slightly posteriorly, narrowing more abruptly over last 20 mm. Tail short (L/T = 70.6), slightly laterally compressed, tip bluntly rounded, in lateral view tapers along dorsal edge, underside flat. In dorsal view, head slightly more U- than V-shaped, as wide as adjacent nuchal region posteriorly, narrowing gently anteriorly to midway between eyes and nares. In ventral view, lower jaws virtually as wide as head, tip more bluntly rounded than snout anteriorly such that mouth marginally subterminal. In lateral view, a dorsal bulge posterior to eyes caused by adductor musculature makes posterior of head deeper than adjacent nuchal region, head tapers very gently anterior to eye level, quite sharply over anteriormost 2 mm, edges of mouth (lips) fairly straight, slightly downturned at CM, CM one and a half times further from top than from bottom of head, lower jaws robust (almost as deep as upper jaws at eye level). Eyes small (0.6 mm), clearly visible through clear skin, slightly elevated above adjacent skin, slightly closer to top of head than to lip in lateral view, inset by about twice their diameters from outline of head in dorsal view; distances between eye and lip almost four times diameter of eye. TAs small (0.6 mm) quartercircle slits curving anteroventrally from anterodorsal edges of eyes, margins slightly elevated. Nares small (0.4 mm), ovate, visible dorsally inset about one and a half diameters from outline of head, posterior part a shallow depression sloping into deeper semi-lunate anterior aperture; in lateral view, each naris visible just behind anterior margin of mouth, inset a little more than one diameter from snout tip, approximately equidistant from top of head and margin of mouth; closer to lips (1.2 mm) than are eyes (1.8 mm), visible in anterior but not ventral views. Teeth strongly recurved, outer rows largest, members of dentary series noticeably larger than ���opposing��� premaxillary-maxillary teeth, IMs larger than ���opposing��� vomeropalatine teeth. Outer rows with few small anteriormost teeth followed on each side by several widely-spaced, hypertrophied (up to 2 mm long), stilettolike teeth with slight medial curvature distally, ending with more recumbent, successively smaller, more closely spaced teeth. Inner tooth rows with similar but less substantial size variation (lacking hypertrophied elements), IM rows bending to form a tight angle anteriorly. Tongue strongly plicate over entire surface, narrow with free tip anteriorly, expands posterolaterally to cover all but six or seven anteriormost IMs on each side. Choanae subcircular, transverse diameters greater than distance between them. Entire palate posterior to choanae with extensive covering of longitudinal plicae. Collar region poorly differentiated. NG 1 faintly indicated midventrally and laterally. NG 2 less faint ventrally, widely incomplete dorsally, somewhat sinusoidal, curving posteriorly from mid-venter and anteriorly across the stripe. NG 3 (arbitrarily the first dorsal groove that clearly crosses stripe onto venter) widely incomplete ventrally. C 1 shorter (3.3 mm) than C 2 (5.7 mm), C 2 with five TGs increasing in length from anterior to posterior, length of anteriormost about one third width of collar. AGs orthoplicate except for slight anteromedial curvature on venter close to vent and last eight with strong anterior flexure middorsally, many offset or otherwise irregular. Many anteriormost (perhaps all but one of first 30) AGs narrowly incomplete ventrally, otherwise mostly complete except for seven interrupted ventrally by disc. Tail (area behind the vent) with six (three ventrally incomplete) AGs. Terminal annulus slightly longer than preceding annuli. Scales begin in TGs of collar region, a single row in shallow pocket at third annulus, tiny on venter, larger and wider than long (e.g., 1.5 x 0.6 mm) on dorsum. At midbody, one or two rows of larger (e.g., 2.2 x 1.1 mm) scales in pockets c. 1.25 times deeper than the length of an annulus. Posteriorly, one main row of large (up to 3.2 x 2.7 mm) scales in very deep pockets (2.5 times length of annulus) with incomplete second row of smaller scales in places. Vent irregular, very slightly longitudinal, formed at centre of an irregular collection of partially subdivided denticulations converging from close to indistinct margins of subcircular cloacal disc. Dark brownish lavender mottled with irregular paler spots, many merging, the paler colour dominating dorsally except for anteriormost c. 65 mm. Thick, fairly uniform, lateral cream stripes extend from close to tail tip to CMs, except for weak interruptions 9���10 annuli anterior to cloacal disc and clearer gaps on C 1, narrower and slightly ventrally expanded on C 2. Small breaks in lateral stripes about 20 annuli from terminus and over last 10 annuli, difficult to ascertain precise end point. Head paler than adjacent body dorsally, with irregular darker blotches. Throat darker than body with less pale mottling bounded by broad pale stripes along the mandibles. Annuli with narrow pale edges. Disc pale, with some dark pigmentation on some, especially posterior, denticulations proximal to vent. Etymology. Named in honour of our esteemed colleague Professor Ronald A. Nussbaum, University of Michigan, USA, in recognition of his many outstanding scholarly contributions to the systematics and biology of caecilians, and celebrating his insights into the fundamental differences between rhinatrematids and all other caecilians. For nomenclatural purposes, the species epithet is considered a noun in apposition. Suggested common name. Ron���s Rhinatrema., Published as part of Wilkinson, Mark & Gower, David J, 2010, A new species of Rhinatrema Dum��ril & Bibron (Amphibia: Gymnophiona: Rhinatrematidae) from Amazonas, Brazil, pp. 63-68 in Zootaxa 2650 on pages 64-67, DOI: 10.5281/zenodo.198783, {"references":["Gower, D. J., Wilkinson, M., Sherratt, E. & Kok, P. J. R. (2010) A new species of Rhinatrema Dumeril & Bibron (Amphibia: Gymnophiona: Rhinatrematidae) from Guyana. Zootaxa, 2391, 47 - 60."]}

The first new species of rhinatrematid caecilian in more than 50 years, Rhinatrema shiv sp. nov., is described from Guyana. The type series of 10 specimens differs from the only other species in the genus, R. bivittatum, in having a longer tail, different colour pattern, more acuminate and relatively shorter head, and in several features of the skull and mandible including dentition. Sequence data for 1572 aligned base pairs of mitochondrial DNA are > 15% different between the two species. Rhinatrema shiv is known only from Guyana, and R. bivittatum from French Guiana and far northeastern Brazil. The only reported specimen of the genus from Suriname is not clearly referable to either of the named species.

Publisher Summary Caecilians are amphibians that look like earthworms. They have blunt, bullet-shaped heads, cylindrical, limbless bodies, and short tails. In some taxa, the primary annuli are further divided into secondary and even tertiary annuli by additional encircling grooves. Most caecilians are fossorial, living inmoist soils usually adjacent to streams, lakes, and swamps; a few species are aquatic. Because of their secretive nature, their biology is largely unknown, and much of the knowledge comes from observations made during capture and captive or museum specimens. All caecilians have internal fertilization. The male copulatory organ, the phallodeum, is an eversible part of the posterior cloaca. Offspring develop internally or externally, depending upon species. If externally, development is indirect or direct; developmental mode is invariable within each species. This chapter describes six families—namely, caeciliidae, ichthyophiidae, rhinatrematidae, scolecomorphidae, typhlonectidae, and uraeotyphlidae of amphibians separately.

A new species of rhinatrematid caecilian, Rhinatrema ron sp. nov., is described based on a single specimen from the state of Amazonas in Brazil. The new species differs from other Rhinatrema in several features, including its larger size, different colouration, and distinctively plicate oral mucosa.

The first new species of rhinatrematid caecilian in more than 50 years, Rhinatrema shiv sp. nov., is described from Guyana. The type series of 10 specimens differs from the only other species in the genus, R. bivittatum, in having a longer tail, different colour pattern, more acuminate and relatively shorter head, and in several features of the skull and mandible including dentition. Sequence data for 1572 aligned base pairs of mitochondrial DNA are > 15% different between the two species. Rhinatrema shiv is known only from Guyana, and R. bivittatum from French Guiana and far northeastern Brazil. The only reported specimen of the genus from Suriname is not clearly referable to either of the named species.

The morphology of the bony palate in larval and metamorphosed Epicrionops bicolor Boulenger and E. petersi Taylor (Rhinatrematidae) was studied to assess the extent of palatal change at metamorphosis. In larvae the maxilla is short; it abuts the dorsolateral process of the palatine at mid-choanal level. The pterygoid is long and straight; it runs anteromedially, close to the lateral edge of the parasphenoid. At metamorphosis the maxilla fuses with the palatine. The maxillary part of the maxillopalatine expands dorsally and caudally, surrounding the orbit and lacrimal ducts and completing the lateral border of the subtemporal fenestra. The anterior part of the pterygoid shifts laterally, broadening the interpterygoid vacuity, and separates from the posterior part of the pterygoid. The quadrate develops a rostrally directed quadratojugal process, overlapped by the maxilla and squamosal. A review of the literature shows that a similar pattern of palatal metamorphosis (except for the division of the pterygoid) is seen in other caecilian genera with free-living larvae: Ichthyophis (Ichthyophiidae), Grandisonia (Caeciliaidae), and probably Uraeotyphlus (Uraeotyphlidae) and Sylvacaecilia (Caeciliaidae). This implies that the shared pattern is plesiomorphic for caecilians. Features of palatal metamorphosis shared among caecilians, salamanders, and frogs support the hypothesis of lissamphibian monophyly. rnal of Herpetol gy, Vol. 30, No. 1, pp. 27-39, 1996 yright 19 6 Society for the Study of Amphibians and Reptiles latal Metamorphosis n Basal Caecilians phibia: Gymnophiona) as Evidence for sa phibian Monophyl Extant amphibians comprise three distinct, monophyletic groups: frogs (Anura), salamanders (Caudata), and caecilians (Gymnophiona) (Duellman and Trueb, 1986; Milner, 1988; Cannatella and Hillis, 1993). The relationship of each group to the others, and of these to fossil taxa, has been much debated. However, an emerging consensus-based on both morphological and molecular evidence-supports the hypothesis first explicitly proposed by Parsons and Williams (1962, 1963; see also Gadow, 1901; 1 Present Address: Department of Molecular and Cellular Biology, University of Arizona, Tucson, Arizona 85721, USA. tant amphibians compris three distinct, onophyletic groups: frogs (Anura), salamaners (Caud ta), and caecilians (Gym ophiona) uellman and Trueb, 1986; Milner, 1988; Canatella and Hillis, 1993). The relationship of ch group to the others, and of the e to fossil Parker, 1956; Szarski, 1962): that the extant groups are a monophyletic unit, the Lissamphibia (e.g., Milner, 1988, 1993; Bolt, 1991; Trueb and Cloutier, 1991; Cannatella and Hillis, 1993; Hedges and Maxson, 1993). Since basal members of all three modern groups have a biphasic life cycle with a discrete metamorphosis from the larval to the juvenile form (Duellman and Trueb, 1986), we might expect to find common character transformations retained in the metamorphosis of each group. Such shared character transformations could serve as additional lissamphibian synapomorphies (cf. de Queiroz, 1985). Both frogs and salamanders undergo profound changes in skull structure at metamorphosis, especially in the palate and the hyoer, 1956; Szarski, 1962): hat the extant ps are a monophyletic unit, the Lissami ia (e.g., Milner, 1988, 1993; Bolt, 1991; Trueb 27 This content downloaded from 157.55.39.32 on Mon, 10 Oct 2016 04:24:55 UTC All use subject to http://about.jstor.org/terms

The classification and phylogeny of the caecilians has received much attention in the past decade, yet no consensus has been reached. We present new mitochondrial ribosomal gene sequence data from 13 caecilian species representing 10 genera from four of the six recognized families. Out of 1208 total sites, 890 were aligned, 475 were variable, and 329 were informative under the parsimony criterion. A phylogeny for these taxa supports the Caudata (as represented by Amphiuma) as the sister lineage to the Gymnophiona, the basal position of the Rhinatrematidae and Ichthyophiidae, the paraphyly of the Caeciliaidae, and the monophyly of the Seychellean caecilians. These sequence data support previous morphological studies suggesting that the typhlonectids were derived from Neotropical caeciliaids, and therefore the Typhlonectidae is synonymized within the family Caeciliaidae. Species previously placed in the Typhlonectidae are assigned to a separate subfamily (Typhlonectinae) of the Caeciliaidae. Resolution of relationships within the largest family, the Caeciliaidae, remains the major task of caecilian systematics.

Descriptions of the trunk musculature of six species representing sex genera and five families of caecilians reveal considerable variation, which may be useful in future systematic studies. The muscle units of the external muscular sheath (M. dorsalis trunci, M. subvertebralis) of caecilians are homologous with, and closely similar in position to, those of salamanders. The major difference in trunk musculature is the presence in caecilians of an additional muscle layer ventral to the M. subvertebralis. This muscle may be a neomorphic derivative from either the M. subvertebralis or the M. transversus. Unlike burrowing reptiles, which have ball-and-socket intervertebral joints, caecilians have retained the primitive amphicoelous centrum and compensate for stresses associated with burrowing by the presence of intercentral ligaments and interlocking basapophyses and subcentral keels. Association of Uraeotyphlus with the Ichthyophiidae and the validity of the Rhinatrematidae are supported by data from the trunk musculature.