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Halicyclops martinezi n. sp. (Figs. 9–16) Type locality. River Godavari (water temperature 25 ºC, pH 7.0) at Kotipalli village (16 ° 41 ′ 36.4 ″N, 82 °03′09. 9 ″E; elevation 10 m) in East Godavari District, Andhra Pradesh, South India (Fig. 1). Type material examined. Holotype female (MNHN-IU- 2013-11851) and allotype male (MNHN-IU- 2013- 11852), dissected on 3 slides each; 65 paratypes: 1 female (MNHN-IU- 2013-11853) and 1 male (MNHN-IU- 2013- 11854), dissected on 3 slides each; 2 females (MNHN-IU- 2013-11855 – 11856) and 1 male (MNHN-IU- 201311857) whole-mounted on 1 slide each; 41 females and 9 males in alcohol (MNHN-IU- 2013-11858); and 5 females and 5 males in senior author’s personal collection; 24 January 2010; Coll. V. R. Totakura. Other material examined: River Godavari: South India, Andhra Pradesh, East Godavari District at Kotipalli village (water temperature 23 ºC, pH 7.5), 0 2 February 2008: 2 males and 8 females; at Kota village (16 ° 41 ′ 36.2 ″N, 82 °03′ 99.9 ″E; elevation 10 m; water temperature 28 ºC, pH 7.0), 14 January 2010: 1 female only; at Brahmapuri village (16 ° 43 ′ 22.1 ″N, 82 °08′ 18.0″E; elevation 8 m; water temperature 28 ºC, pH 7.0), 24 January 2010: 1 male, 4 females; Coll. V. R. Totakura. Diagnosis. Total body length of female 382–418 Μm; of male 361–435 Μm; cephalothorax subquadrate, without dorsal integumental window, about as long as its greatest width distally and 37.1 % of total body length; hyaline fringes on all segments denticulate; pseudosomite present between prosome and urosome; genital doublesomite as long as wide, without lateral projections; ornamented with latero-ventral window on either side of distal half; pseudo-operculum on preanal somite extending up to midlength of anal somite; female antennule 6 - segmented, fourth segment 1.9 times as long wide; antenna 4 -segmented, second endopodal segment 5.8 times as long wide, with 5 setae on inner margin; mandibular palp represented by 2 reduced, unequal simple setae; maxillulary basis with basally swollen inner medial plumose seta, exopodal seta half as long as endopod seta; maxilla 4 -segmented; maxilliped 2 -segmented; legs 1–4 spine formula: 3.4. 4.3, and setal formula: 5.5.5.4; leg 4 third endopodal segment with spiniform inner setae; caudal rami slightly divergent, each ramus about twice as long as maximum width; ornamentation on principal outer apical seta and principal inner apical seta heteronomous; lateral seta arising from 3 / 5 of ramus length and 1.3 times as long as maximum width of ramus; outermost apical seta 2.1 times as long as ramus; innermost apical seta 1.8 times as long as outermost apical seta; principal inner apical seta 6.8 times as long as caudal ramus. Leg 5 basis and endopod completely fused to somite; outer basal plumose seta inserted on basal protuberance; exopod armed with 3 strong spines and 1 apical plumose seta. Leg 6 with 2 spiniform setae and 1 small and slender seta. Genital field located anteriorly. Description of adult female. Total body length, measured from base of rostrum to posterior margin of caudal rami (excluding caudal setae), 486 Μm. Preserved specimens colourless. Naupliar eye absent. Body (Fig. 9 a) robust, perforated, cyclopiform, with prosome/urosome ratio 1.3 and greatest width at posterior end of cephalothorax (159 Μm). Body length/width ratio 2.7. Cephalothorax (Fig. 9 a) about as long as its greatest width at distal end, 37.1 % of total body length, 2.4 times as wide as genital double-somite, and not produced posterolaterally; hyaline fringe well developed dorsally; ornamented with several small sensilla as illustrated, and without suture on dorsal surface. Rostral projection (Figs. 9 a, 10 a) moderately developed, broadly triangular in dorsal view, with 2 small sensilla on dorsal surface. Second and third free pedigerous somites pointed postero-laterally, ornamented with 4 and 6 sensilla, respectively. Fourth pediger with rounded corners. Pseudosomite present between prosome and urosome. Fifth pedigerous somite about as wide as genital double-somite. Free pedigers 2–3 with well developed denticulate hyaline fringe on distal margin dorso-ventrally. Urosome (Figs. 9 a, b, 10 b): fifth pedigerous somite with hyaline fringe dorso-ventrally and ornamented with 4 sensilla. Genital double-somite elliptical, 0.9 times as long as wide; hyaline fringe with denticulate margin both dorsally and ventrally; ornamented with 1 vague trapezoidal integumental window in proximal dorsal half, 1 large lateral, cuticular window on either side, 2 large cuticular recesses on each side at midlength, 7 dorsal and 4 ventral pores (Fig. 10 d) and 6 sensilla dorso-posteriorly (Fig. 10 c). Copulatory pore (Fig. 10 d) small; copulatory duct narrow, short and sclerotized. Seminal receptacle very small, ovoid. Ovipores situated dorso-laterally, covered with reduced sixth legs. Sixth legs (Fig. 10 c, e) bearing 3 short, spiniform elements, innermost one somewhat slender. Preanal somite with denticulate hyaline fringe both dorsally and ventrally, but 2 medial dorsal denticles (pseudooperculum) protruding and extending up to distal-third of anal somite (Fig. 9 b). Anal somite (Figs. 9 a, 10 b) ornamented with 2 small sensilla on dorsal surface, and transverse row of spinules on posterior margin. Anal operculum smooth and moderately developed, representing 50.8 % of anal somite’s width. Anal sinus widely open; ornamented with 2 diagonal rows of fine spinules. Caudal rami (Figs. 9 a, 10 b): slightly divergent, with basal space between them about 0.7 times as wide as ramus’ width; ramus 1.9 times as long as maximum width, ornamented with spinular row on distal margin ventrolaterally at base of outermost apical seta and at inner distal corner; dorsal seta about 0.6 times as long as principal outer apical seta, inserted at distal fifth of ramus length and uniarticulate at base; lateral seta arising from dorsal surface close to outer margin at 3 / 5 of ramus length and 1.3 times as long as maximum width of ramus; outermost apical seta 1.2 times as long as ramus, inserted subapically; principal apical setae with breaking planes; inner seta 1.7 times as long as outer seta, 1.2 times as long as urosome, and 6.5 times as long as caudal ramus. All caudal setae plumose. Antennule (Fig. 11 a): 6 -segmented, extending up to 4 / 5 of cephalothorax and ornamented with 1 crescentic row of spinules proximally on first segment. Setal formula: 8.12.3+aes. 6 +aes. 2.9 +aes. Length ratios of antennular segments along medial axis 1.0: 0.8: 0.4: 1.2: 0.6: 1.0. Segments 1–6 with 3, 3, 3, 4, 2, and 4 long pinnate setae, respectively; all other setae smooth. Probable segmental homology 1 (I–V), 2 (VI–XI), 3 (XII–XIV), 4 (XV–XX), 5 (XXI–XXIV), 6 (XV–XVIII). Antenna (Fig. 11 b): 4 -segmented, comprising coxa, basis and 2 -segmented endopod. Coxa small and unarmed. Basis about as long as first endopodal segment, ornamented with short U-shaped row of tiny spinules near proximal outer corner; armed with 1 smooth seta and 1 pinnate seta at inner distal corner; exopodal seta absent. First endopodal segment 1.9 times as long as wide, armed with 1 smooth seta. Second endopodal segment 5.2 times as long as wide, about twice as long as first one, armed with 5 lateral and 7 apical setae, ornamented with 1 oblique row of spinules on proximal surface and 2 longitudinal rows of small spinules on outer margin. Labrum (Fig. 12 a): trapezoidal; anterior edge straight, narrow with 11 small teeth between large lateral teeth; ornamentation not discernible. Mandible (Fig. 12 b): coxal gnathobase roughly divided into 3 groups of teeth; inner group of only 2 large unequal teeth, innermost one being larger; middle group of 3 small, more or less equal small teeth and 3 strong spinules between small teeth; outer group comprising 1 simple slender tooth and 1 pinnate outermost seta. Palp represented by 2 small, unequal setae. Maxillule (Fig. 12 c): composed of well developed praecoxa and 2 -segmented palp. Arthrite of praecoxa bearing 4 very strong spinous processes and 7 armature elements along inner margin (second proximal one longest and pinnate). Palp composed of coxobasis and endopod. Coxobasis 1.8 times as long as wide, with smooth proximal exopodal seta and 2 apical setae (inner one basally dilated, pinnate) and 1 subapical smooth seta; endopod small and distinct at base, with 3 smooth setae (2 apical setae, 1 inner subapical seta). Maxilla (Fig. 12 d): 3 -segmented, praecoxa partially fused with coxa. Proximal endite of praecoxa small, armed with 2 unequal plumose setae; distal endite small, unarmed. Proximal endite of coxa with 1 short pinnate seta; distal endite highly mobile, bearing 1 completely fused and very stout pinnate seta and 1 small pinnate seta. Basis drawn out into spinulose robust claw and armed with 2 unequal setae; strong seta about as long as claw. Endopod armed with 2 spinulose claws and 3 smooth setae. All strong setae as well as basal claw prehensile. Maxilliped (Fig. 12 e): 2 -segmented, composed of protopod and 1 -segmented endopod. Protopod 3.2 times as long as wide and armed with 2 strong spiniform setae and 1 smooth normal seta; unornamented. Endopod half as long as protopod, armed with 2 strong bipinnate setae and 2 smooth setae and 1 bipinnate strong, claw-like apical seta; apical seta longest, 1.7 times as long as segment and fused at base; unornamented. Legs 1–4 (Fig. 13 a–d): with 3 -segmented exopod and endopod. Praecoxae of all legs short, unornamented. Coxa ornamented with 1 row of spinules at outer distal margin. Basis slightly larger than coxa, ornamented with 1 row of spinules on distal margin between exopod and endopod and another row at inner distal corner. Inner coxal spine and outer basipodal seta present on all legs; leg 1 basis alone with moderately strong inner spine. Endopod nearly as long as exopod on legs 1–4. Third exopodal segment spine formula: 3.4. 4.3, and setal formula: 5.5. 5.4. Intercoxal plate with 2 small, rounded prominences ornamented with 3 rows of fine spinules. Spine and setal formulae (legend: same as that of Paracyclopina orientalis): Coxa Basis Exopod Endopod 1 2 3 1 2 3 Leg 1 1 -0 I- 1 1 -I 1 -I 4, 1+I, II 1 -0 1 -0 2, 1+I, I Leg 2 1 -0 0-1 1 -I 1 -I 4, 1+I, III 1 -0 1 -0 2, 1+I, II Leg 3 1 -0 0-1 1 -I 1 -I 4, 1+I, III 1 -0 1 -0 2, 1+I, II Leg 4 1 -0 0-1 1 -I 1 -I 3, 1+I, II 1 -0 1 -0 II, II, I Leg 5 (Figs. 9 a, b, 10 b, c): basis and endopod completely fused to somite; outer basal plumose seta inserted on basal protuberance, which is 1.2 times as long as wide. Exopod about 1.3 times as long as wide; ornamented with 1 row of small spinules along outer margin; armature consisting of 3 strong spines and 1 apical plumose seta; inner spine 0.4 times as long as segment, slightly longer than outer apical spine and proximal outer spine; apical seta 1.5 times as long as segment and about as long as basal seta. Leg 6 (Figs. 9 a, 10 e): trapezoidal plate, armed with 2 almost equal, smooth dentate spines and 1 smooth and slender spiniform seta, which is slightly longer than spines. Description of adult male. Total body length, excluding caudal setae, 392 Μm. Habitus (Fig. 14 a) somewhat slenderer than female. Prosome/urosome ratio 1.7, greatest width (139 Μm) at posterior end of cephalothorax. Body length/width ratio 2.6. Cephalothorax 37 % of total body length; anterior one-fifth narrow; postero-lateral corners not produced. Hyaline fringes of all somites well developed with denticulate margin. Fifth pedigerous somite with oblique outer margin. Genital somite (Figs. 14 a, b, 15 a, b) 1.3 times as wide as long in dorsal view. Third urosomite ornamented with 1 pore mid-ventrally (Fig. 15 b) and 1 large latero-ventral integumental window on either side (Figs. 14 b, 15 b); fourth urosomite ornamented with 2 latero-ventral pores (Fig. 15 b). Preanal somite, anal somite, and anal operculum similar to female. Caudal rami (Figs. 14 a, b, 15 a, b) almost similar to female, 1.4 times as long as anal somite; each ramus 1.7 times as long as maximum width; armature and ornamentation almost as in female. Antennule (Fig. 16): 12 -segmented, digeniculate, geniculation between segments 5 and 6 and 11 and 12. First segment with 1 short row of spinules at base. Setal formula: 11 + 2 aes. 2.5 +aes.0.0.1aes. 1.2 +aes. 1 +aes. 2 +aes. 1.10 + 3 aes., all aesthetascs smooth and simple; segments 8–11 each with 1 small, modified unipinnate seta; segments 1, 2, 3, 12 with 4, 2, 1 and 6 long bipinnate setae respectively; all other setae smooth. Length ratios of antennular segments along medial axis 1.0: 0.2: 0.3: 0.2: 0.3: 0.3: 0.4: 0.2: 0.3: 0.3: 0.7: 1.3. Labrum (Fig. 15 c): anterior edge with about 20 small and equal teeth between triangular lateral projections; ornamented with 6 elongate hair-like spinules on dorsal surface and transverse row of 6 large spinules on ventral surface. Other cephalic appendages and legs 1–5 as in female. Leg 6 (Figs. 14 b, 15 b): distinct, large plate, armed with 3 unequal armature elements. Etymology. The new species is named in honour of Dr. P. Martínez Arbizu for his significant contributions to the systematics of copepods; the specific epithet is a noun in the genitive singular. Gender masculine. Remarks. The genus Halicyclops Norman, 1903 is highly speciose and cosmopolitan in distribution. The World Copepoda database on the genus Halicyclops (Boxshall 2011) contains a list of 76 species and 13 subspecies, which are apparently valid (‘direct child species’). Karanovic (2006) divided the genus into two subgenera: Rochacyclops Karanovic, 2006, and Halicyclops s. str. Now, the former includes two species from Australia, and one each from Belize, Mexico, and Malaysia, whereas all other taxa belong to Halicyclops s. str. In India, only six species are so far known, and all of them belong to Halicyclops s. str. The Indian species and their distribution records are as follows: Halicyclops (Halicyclops) tenuispina Sewell, 1924, from Lake Chilka, Odisha State; Halicyclops (Halicyclops) spinifer Kiefer, 1935, from Lake Kolleru, Andhra Pradesh state; Halicyclops (Halicyclops) canui Lindberg, 1941, from a swamp at Bandra, West Mumbai (erstwhile Bombay); Halicyclops (Halicyclops) electus Lindberg, 1943, from Mahim, Mumbai; Halicyclops (Halicyclops) konkanensis Lindberg, 1949, from Konkan, west coast; Halicyclops (Halicyclops) pilifer Lindberg, 1949 from Thane, west coast near Mumbai; and Halicyclops (Halicyclops) martinezi n. sp. from the River Godavari, Andhra Pradesh. Halicyclops (Halicyclops) has eight groups (Group A–H) based on the spine formula of the third exopodal segment of legs 1–4 (see Pesce 2013). In India, as of now, groups A, B and F exist, and they are characterised by the spine formula 4.4. 4.3, 3.4. 4.3, and 2.3. 3.3, respectively. The position of the lone species of group A, i.e. H. (H.) tenuispina is doubtful because, Sewell (1924: 797, Pl. 47, Fig. 3) reported its spine formula as 4.4. 4.3, but the figure of leg 4 exopod has four outer spines. Halicyclops (H.) martinezi n. sp. belongs to the species Group B by possessing, inter alia, the following combination of characters: the spine and setal formulae of the third exopodal segment of legs 1–4 are 3.4. 4.3 and 5.5. 5.4, respectively; the female genital double-somite is devoid of any protuberance on either side; all the five armature elements of the third endopodal segment of leg 4 are transformed into spiniform structures; the hyaline fringes on all somites denticulate; pseudo-operculum (hyaline fringe of penultimate segment) extending up to 2 / 3 of anal somite and bifurcate distally; leg 5 has three spines and one seta in both sexes; its exopod is 1.3 times as long as wide, and ornamented with one row of small spinules along outer margin; the inner apical spine is about half as long as its segment, slightly longer than the outer apical spine and about as long as the proximal outer spine; the apical seta 1.5 times as long as segment and about as long as the basal seta; the caudal ramus 1.9 times as long as maximum width and has no tube near the cuticular protuberance of the dorsal seta. The Group B is a rather complex group, comprising most of the known species and subspecies of Halicyclops, which are distributed almost throughout the world (Pesce 2013). H. (H.) martinezi n. sp. stands out in the Group B by the inner spine of leg 5 in both sexes being slightly longer than other elements except seta, and the fourth antennular segment in the female about twice as long as wide. It can be easily distinguished from all the Indian congeners by the protruding pseudo-operculum on the preanal somite and the presence of a single seta on the second endopodal segment of legs 1–4.

Key to the Indian species of the genus Halicyclops Norman, 1903 1. Spine formula 2.3. 3.3........................................................... H. (H.) canui Lindberg, 1941 - Spine formula 4.4. 4.3......................................................... H. (H.) tenuispina Sewell, 1924 2. Genital double-somite with lateral process, spine formula 3.4. 4.3............................................... 3 - Genital double-somite without lateral process, spine formula 3.4. 4.3............................................. 4 3. Genital double-somite with long lateral spinous process................................. H. (H.) spinifer Kiefer, 1935 - Genital double-somite with small, blunt lateral process............................... H. (H.) electus Lindberg, 1941 4. Second endopodal segment of legs 2���4 with 1 inner seta..................................... H. (H.) martinezi n. sp. - Second endopodal segment of legs 2���4 with 2 inner setae..................................................... 5 5. Caudal ramus 1.5 times as long as wide, length-width ratio of leg 4 third endopodal segment 2.2................................................................................................ H. (H.) konkanensis Lindberg, 1949 - Caudal ramus 1.2 times as long as wide, length-width ratio of leg 4 third endopodal segment 1.2..................................................................................................... H. (H.) pilifer Lindberg, 1949, Published as part of Totakura, Venkateswara Rao & Reddy, Yenumula Ranga, 2015, Groundwater cyclopoid copepods of peninsular India, with description of eight new species, pp. 1-93 in Zootaxa 3945 (1) on page 30, DOI: 10.11646/zootaxa.3945.1.1, http://zenodo.org/record/288235, {"references":["Lindberg, K. (1941) Cyclopoides nouveaux du continent Indo-Iranien. I. Records of the Indian Museum, 43, 87 - 95.","Sewell, R. B. S. (1924) Fauna of the Chilka Lake. Crustacea, Copepoda. Memoirs of the Indian Museum, 5, 771 - 851.","Kiefer, F. (1935) Zur Kenntnis der Halicyclopiden (Crustacea Copepoda). Zoologischer Anzeiger, 100, 10 - 13."]}

The lectotype of H. sarsi Akatova, 1935 is designated and described. H. pygmaeus Sars, 1927 (nomen nudum) and H. setifer Lindberg, 1949 are placed in synonymy under H. sarsi.

A number of harpacticoid and cyclopoid copepods were collected during two short-term studies examining the effects of organic enrichment on the distribution and density of meiofauna in two coastal systems in central (Ensenada del Pabellon lagoon) and southern (Urias system) Sinaloa, north-western Mexico. Harpacticoids were by far the most common Copepoda, followed by cyclopoids and poecilostomatoids. The present contribution provides the complete description of a new species of the so far monotypic genus Kristensenia Por, 1983, known from Bonaire (Netherlands Antilles) and Celestun lagoon (Yucatan, Mexico), and the first record and range extension of Halicyclops hurlberti Rocha, 1991, previously known from Tihuana estuary near San Diego (California, USA). An updated generic diagnosis for Kristensenia Por, 1983 is presented.

Plankton samples obtained from the lagoon system Laguna Navío Quebrado, in northern Colombia, yielded male and female specimens of an undescribed cyclopoid copepod of the genus Halicyclops. The new species belongs to the highly diverse and widely distributed thermophilus-complex. It closely resembles Halicyclops clarkei Herbst, 1982 from Louisiana and Halicyclops bowmani Rocha & Iliffe, 1993 from Bermuda. These species share the same armature of P1-P4EXP3, with a 3443 spine formula and the terminal antennary segment with 5 setae. However, Halicyclops gaviriai sp. n. can be separated from both Halicyclops clarkei and Halicyclops bowmani by the morphology of the anal pseudoperculum, the proportions of the fourth antennulary segment, the length of the inner basipodal spine of P1, the P1EXP/inner basipodal spine inner length ratio and the length/width ratio of the caudal rami. This is the third species of Halicyclops recorded from Colombia and the first one described from this country. With the addition of Halicyclops gaviriai sp. n., the number of species of Halicyclops known from the Neotropics increases to 19. The regional diversity of the genus is probably underestimated.

Halicyclops cenoticola sp. nov. is described from cenotes of the Yucatan Peninsula, Mexico. The new species shares exclusively with H. caridophilus and H. tetracanthus the presence of 2 inner setae on the leg 5 exopod in the males. As far as is known, the new species is distinguished trom all its congeners in having the dorsal caudal seta as long as the outer middle caudal seta; legs 2 and 3 are dimorphic concerning the structure of the 3 inner setae on the terminal endopodal segment; and leg 6 of both the male and female consists of only 2 elements. An identification key for the Halicyclops species known trom the Caribbean Region, the Gulf of Mexico, Bermuda, and the coast of French Guiana is included.

H. tageae sp. n. and Halicyclops ytororoma sp. n. are described from the intertidal interstitial water of Brazilian beaches.

Two new species of Halicyclops, H. reidae and H. maculatus, are described from the groundwater and marsh sediment of Wye Island, Maryland. Halicyclops maculatus is the rst species of the genus to show sexual dimorphism in the males consisting of digitiform setae on the endopodite of swimming legs 1 and 2. Halicyclops reidae is the only American species of the genus having the inner distal seta of the leg 4 endopodite 3 plumose and the proximal seta spiniform.

Species of the cyclopid genus Halicyclops are widespread in coastal, estuarine and even fluvial environments worldwide. On the Atlantic coast of South America several species have been recorded as far south as the state of São Paulo in Brazil, at about 24°25´S. Specimens belonging to this genus have been collected from plankton samples from Laguna de Mar Chiquita, a coastal lagoon on the Argentinean coast at 37°40' S, 57°19' W. These do not fit the diagnosis of any of the known species, and are here described as a new species. Both sexes of Halicyclops ramirezi sp. nov. are described and illustrated. It is distinguished by a combination of characters relating to (1) the last endopodal segment of P4, (2) shape and armature of P5, (3) size and spinulation of the spine on the basipodite of P1, and (4) length/width ratio of the fourth A1 segment. The presence of only one seta and three spines on the male P5 is also characteristic. The presence of Halicyclops glaber Rocha, 1983 is reported for the first time for Argentina in sediments of the same locality.

Halicyclops ramirezi sp. nov. (Figs 2���28) Material examined. 3 females and 3 males from Laguna Mar Chiquita (37 �� 40��S, 57 �� 19��W) (Fig. 1). Female holotype (MACN-In 36391), male allotype (MACN-In 36392) and four dissected paratypes (MACN-In 36393), two females and two males. Description. Female. holotype total length, excluding caudal setae, 0.7 mm. Prosome: urosome ratio of holotype: 1.5. Postero-dorsal border of all prosomites smooth (Fig. 2). Genital double-somite (Fig. 3) as long as wide, with 2 large triangular protrusions located laterally in the anterior third, similar to those of H. pilosus Rocha, 1984 and small lateral integumentary windows on the posterior third. Such structures are present also in H. venezuelaensis Lindberg, 1954 (as illustrated by Rocha 1995 a), but here are slightly triangular. Seminal receptacle not visible (Fig. 3). Copulatory pore located centrally at the proximal third of the somite. Posterior edges of urosomites with denticulate hyaline membrane, larger in genital double-somite and decreasing in size in 2 subsequent urosomites, with denticles far more conspicuous on ventral than on dorsal surface (Figs 3���4). Anal pseudoperculum unarmed and with rounded margin. Anal somite deeply incised, with distal edge smooth dorsally and denticulate ventrally. Anal area with semicircular row of long spinules on each side. Caudal rami as long as wide (Fig. 3). Lateral seta inserted on a raised base located at end of slightly broader proximal third of caudal ramus, somewhat longer than or equal to the width of ramus itself. Dorsal seta with articulated base, inserted on distally-located papilla and longer than lateral seta. Outer apical seta longer and stiffer than inner apical seta. Inner median seta representing about 60 % of total body length, 2.3��� 2.5 longer than outer median seta, with basal portion ornamented with sparse short setules and terminal portion with longer, more numerous setules on both sides, becoming gradually thinner towards apex. Outer median seta (Figs 5���6) also setulose, but setules shorter and not so densely packed. Antennule (Fig. 7) 6 -segmented, with the same structure and armature as other species of genus, e.g. H. venezuelaensis (as redescribed by Rocha 1995 a), H. hurlberti Rocha, 1991 and H. tetracanthus Rocha, 1995: 8, 12, 5 + spine, 6 + aesthetasc, 2, 10 + aesthetasc (Rocha 1995 a). Fourth segment about 1.8 longer than wide, its anterior margin notched at insertion of each marginal seta. Antenna (Fig. 8) 3 -segmented. Reduced coxa unarmed, fused to basis; basis with 2 plumose setae at inner distal corner; exopod represented by hyaline, sparsely plumose seta, reaching base of terminal segment. Endopod 2 -segmented; first segment bearing a single submarginal seta in distal third. Last segment bearing 5 setae along inner margin distributed 1-2 - 2 on 3 notches, and 7 setae of diverse lengths at tip; outer margin with transverse rows of spinules forming 3 archs. Mandible (Fig. 9) consisting of gnathobase provided with sharp toothed pars incisiva and reduced palp with 2 naked setae, the longest barely reaching base of teeth. FIGURES 12���21. Halicyclops ramirezi sp. nov. female. 12: maxilliped; 13: maxilliped; 14: P 1; 15: P 2; 16: P 3; 17: P 4; 18: terminal endopodal segment of P 4, whole specimen; 19: terminal endopodal segment of P 4, permanent slide; 20: P 5; 21: P 5 and P 6. Figs 13 ���15, 18, 20, from paratype 1; 12, 16���17, 19, 21 from paratype 2. Scale bars: 0.1 mm. Maxillule (Fig. 10) comprising strong praecoxa and 2 -segmented palp. Distal end of praecoxa bearing 4 strong, curved, claw-like spines, 3 fused to segment and the largest articulated and bearing a stiff setule; inner surface bearing 7 conical spines of different lengths. Palp showing 4 spiny setae on proximal segment and 3 setae on distal one. Maxilla (Fig. 11) consisting of 4 segments. Praecoxa fused to coxa and bearing 2 setae ornamented with stiff setules. Naked seta present on raised swelling on coxa; single coxal endite bearing naked seta and a strong distal seta, ornamented with 3 long, stiff setules. Basis produced into strong serrate claw, ornamented with strong serrated spine and thin seta. Unsegmented endopod carrying 2 spines, thin seta and 2 short hairlike setae. Maxilliped (Figs 12���13) 2 -segmented. Basal segment armed with 2 long spiny setae, 2 spinules on opposite edge and a row of spinules distally. Apical segment armed with 5 setae, 2 of which are ornamented with conspicuous stiff setules. Swimming legs 1���4 (Figs 14���21) armature as in Table 1. P 1 (Fig. 14) basis with spine at inner corner reaching third endopodal segment and armed with very long, needle-like, stiff setules, arising in a helicoidal pattern. P 4 third endopodal segment (Figs 17���19) 1.4 longer than wide; inner apical spine 1.5 times longer than segment and on average 1.3 longer than outer apical spine: inner rim with 2 stiff, spine-like setae. Distal inner seta shorter than segment, not reaching tip of inner apical spine, almost even with external spine. P 5 (Fig. 20���21) exopod about 1.5 times longer than broad, bearing 3 spines and 1 seta. Seta slightly longer than inner spine, which is longest of the 3, almost as long as segment. Minute spinules present on external and internal margins. P 6 located on dorsal side of lateral protrusions, represented by inner seta and 2 blunt protrusions (Fig. 21). Male (Figs 22���28). Allotype (Figs 22���23) total length, excluding caudal setae, 0.53 mm. Only dimorphic traits described and illustrated. Prosome: urosome ratio of allotype about 1.7. Genital somite slightly wider than long (L/W= 0.85). Following urosomite with somewhat triangular integumentary windows in the posterior half. Inner median seta proportionally longer than in female, representing about 65 % of total body length Antennule (Fig. 24) 14 -segmented; it ends in a spatulate tip when seen in dorsal view, and presenting a complicated set of serrate spines on inner edge of joint between 12 th and 13 th segments (Fig. 25). Distal segment of P 4 endopod (Fig. 26) slightly more slender than in female, 1.5 times longer than wide; inner finely-serrate spine-like setae much longer than in female, both surpassing by far tip of external seta. Distal inner seta longer than segment. P 5 (Figs 27���28) with same armature distribution as female; tiny spinules on external margin longer and more visible. Spines much longer than in female, longest around 1.4 times longer than segment. P 6 (Fig. 28) spine reaching almost to distal edge of the segment, with a row of minute spines at base; setae finely plumose, internal longer than middle one. Etymology. The species is dedicated to Dr. Fernando C��sar Ram��rez, zooplanktologist at INIDEP (and previously at the Instituto de Biolog��a Marina) at Mar del Plata, mentor to generations of Argentinean planktologists. Habitat. H. ramirezi sp. nov. is known only from plankton samples taken at the type locality, where it is completely outnumbered by the benthic congener H. glaber. The few collected specimens appeared in samples considered to be close to freshwater, on account of their low conductivity. More detailed sampling is needed to detect microhabitat preferences of the new species in a complex environment with fluctuating salinity levels. Differential diagnosis. Halicyclops ramirezi sp. nov. belongs to the group of species recognized by Rocha (1991) as sharing the following traits: - caudal setae bearing only setules as ornaments and these heteronomously distributed,- fourth segment of female antennule less than twice as long as wide,- inner spine of the second basipodite of P 1 reaching at least midlength of the third endopod of that swimming leg. - In addition it shares with many species of this group the spine formula 3-4 - 4 - 3 for the last exopodal segment of P 2 ���P 4. The new species most closely resembles H. glaber and H. venezuelaensis. The female can be readily distinguished from the former by the presence of two slender, finely serrate spines, on the inner margin of the third endopodal segment of P 4, and from the latter by the shape of the genital double-somite, by the proportional lengths of the setae on the last endopodal segment of P 4 and on the exopod of the P 5. The male is easily distinguished from those of both species by the P 5 armature, which consists in H. ramirezi of four elements (three spines and one seta) rather than five elements (three spines and two setae).The presence of small lateral integumentary windows in the last third of the genital double-somite of the female and the second urosomite of the male is a trait shared with H. venezuelaensis, from which the new species differs by the slightly triangular shape of these structures., Published as part of Menu-Marque, Silvina & Sorarrain, Dora, 2007, The southernmost South American record of the genus Halicyclops Norman, 1903 (Cyclopoida: Cyclopidae) with the description of a new species, pp. 47-55 in Zootaxa 1607 on pages 49-54, DOI: 10.5281/zenodo.178839, {"references":["Rocha, C. E. F. (1984). Four new species of Halicyclops Norman (Copepoda, Cyclopoida) from Brazil. Hydrobiologia, 119, 107 - 117.","Lindberg, K. 1954. Cyclopides (Crustaces, Copepodes) de l'Amerique du Sud. Arkiv for Zoologi 7 (11), 193 - 222.","Rocha, C. E. F. (1995 a). Copepods of the genus Halicyclops (Cyclopidae) from Belize. Hydrobiologia, 308, 1 - 11.","Rocha, C. E. F. (1991). A new species of Halicyclops (Copepoda, Cyclopidae) from California, and a revision of some Halicyclops material in the collections of the US Museum of Natural History. Hydrobiologia, 236, 29 - 37."]}

Halicyclops caneki n. sp. is described from Celestun Lagoon (northwest of the Yucatan Peninsula) and is compared with its congeners H. herbsti Rocha and Iliffe, and H. bowmani Rocha and Iliffe, known from the Bermuda cave system. H. magniceps previously reported from the peninsula is considered as a possible junior synonym of H. caneki. The new species was found among several other copepods living between the aufwuchs covering submerged mangrove pneumatophores.

Conception of Crossed Populations: Application in Cyclopoida TaxonomyThe conception of crossed populations in wide practice of taxonomic investigations in Cyclopoida is used for the first time. Applying this conception in taxonomy of cyclopoid copepods we based on revealed facts of the coexistence of sibling species which keep a little morphological hiatus. Hence, next pairs of species we consider as independent ones:Eucyclops speratus(Lilljeborg) andE. serrulatus(Lilljeborg);Paracyclops poppei(Rehberg) andP. fimbriatus(Fischer);Megacyclops latipes(Lowndes),M. viridis(Jurine) andM. gigas(Claus);Diacyclops clandestinus(Kiefer) andD. languidoides(Lilljeborg);D. hypnicola(Gurney) andD. languidoides(Lilljeborg);D. odessanus(Schmankevitsch) andD. bicuspidatus(Claus);Microcyclops rubellus(Lilljeborg) andM. varicans(Sars);Halicyclops septentrionalis(Kiefer) andH. neglectus(Kiefer). Facts of coexistence ofAcanthocyclops americanus(Marsh) and its formA. americanusf.spinosa(Monchenko) differing by only one qualitative feature (spine or seta on outer edge on endopodite P4 distal segment) that has no transitive manifestation do not allow us to consider morphological formA. americanusf.spinosaas a separated species from the typeA. americanus.

Four new species of Halicyclops are described and figured from plankton samples of the brackish waters of Pomonga River, Sergipe State (NE Brazil). The ornamentation of the median apical setae of the furcal rami is proposed as useful diagnostic character for species distinction.

Halicyclops aberrans sp. n. e descrito de material proveniente de duas localidades do Rio Capim (Estado do Para), ocupadas por agua doce. Ela difere de todas as especies conhecidas de Halicyclops por ter o espinho apical interno do ultimo articulo do endopodito do terceiro e quarto par de patas natatorias reduzido e inclinado para cima, e pelo numero de espinhos no ultimo articulo do exopodito dos quatro pares de patas natatorias (2.3.3.2).

Hadicyclops fosteri ist eine planktonische Art, die bisher nur selten in Astuarien Nordamerikas gefunden wurde. Sie erweist sich als eine der dominierenden Formen in zwei kleinen Zuflussen am sudwestlichen Ufer der Delaware Bucht. Beide Flusse sind weniger als 20 km lang und haben ein schwaches Gefalle; sie entwassern ausgedehnte Sumpfgebiete. Die Populationen von H. fosteri erreichen ihr Maximum bei Temperaturen uber 20° C und bei Salinitaten unter 2‰. Es konnten zwischen 10 000 und 750 000 Individuen pro m3 gezahlt werden. H. fosteri und Eurytemora affinis (Calanoida) sind in beiden Flussen in den Regionen mit niedrigem Salzgehalt die dominierenden Copepoden.

Four Cyclopoida have been described and illustrated from saline inland waters in Australia. Two of these are known species: Metacyclops arnaudi (G. O. Sars, 1908) and Apocyclops dengizicus (Lepeschkin, 1900). The two others are considered as new: Halicyclops ambiguus n. sp. and Metacyclops arnaudi platypus n. subsp.

Two new cyclopoid species belonging to the genus Halicyclops Norman, 1903 are described from brackish waters in South Korea: H. lanceolatus sp. nov. and H. pumilus sp. nov. Halicyclops lanceolatus was collected from two river mouths, both connected to caves. It belongs to the thermophilus group in showing 3,4,4,3 spine formula on legs 1-4 and lateral process on the genital double-somite. Among the members of the species group, it is closely allied with H. thermophilus Kiefer, 1929 and H. uncus Ueda and Nagai, 2009. However, it differs from them by a stout, lanceolate inner apical spine on leg 5 exopod, very short lateral process of the genital double-somite, short caudal rami, and shorter inner apical spine on the third endopodal segment of leg 4. Halicyclops pumilus was collected from interstitial waters of estuarine sandy beaches, and it is characteristic in having a single inner seta on the second endopodal segments of legs 2-3, and quadrate shape of leg 5 exopod with stumpy spines.