Hynobius unisacculus sp. nov. (Figs. 3���6; Table 3) Synonymy: ��� Hynobius leechii (partim): Sato 1943: p. 33; Chang et al. 2011: p. 20.��� ��� Hynobius quelpaertensis (partim): Kim et al. 2003: p. 1166.��� ��� Hynobius leechii Clade HC2: Baek et al. 2011a: p. 108; Baek et al. 2011b: pp. 25���32.��� Holotype. CGRB-15401 (deposited in the Conservation Genome Resources Bank for Korean Wildlife (CGRB), College of Veterinary Medicine, Seoul National University; field number MMS 1962), adult male from the Naro Islands (Oenaro-do Island), from the environs of Oecho-ri, Bongrae-myeon, Goheung-gun, Jeollanam-do, South Korea (127�� 28��36.1¨ E; 34�� 26��19.6¨ N), collected on March, 10, 2010 by Hae-Jun Baek and Mi-Sook Min. Paratypes. With the exception of the holotype, the type series consists of 68 adult specimens: 55 males and 13 females, all collected during the breeding season. Type series includes: ten specimens (CGRB-15392���400, 402; field numbers: MMS 1951���53, 1955���58, 1960- 1961, 1963; 8 males, 2 females) with the same collection data as the holotype; six specimens (CGRB-15386���391; field numbers: MMS 1945���50; 3 adult females, 3 subadults) from the vicinity of Singeum-ri, Bongrae-myeon, Goheung-gun, Jeollanam-do, South Korea (Oenaro-do Island), collected on March, 10, 2010 by Hae-Jun Baek and Mi-Sook Min; two specimens (CGRB-15403���404; field numbers: MMS 1968���1969; 1 male, 1 female) from the environs of Bongrim-ri, Podu-myeon, Goheung-gun, Jeollanam-do, South Korea, collected on March, 11, 2010 by Hae-Jun Baek and Mi-Sook Min; four specimens (CGRB-15442���445; field numbers: MMS 1972���73, 1975, 1981; 3 males, 1 female) from the vicinity of Jinggwang-ri, Beolgyo-eup, Boseoung-gun, Jeollanam-do, South Korea, collected on March, 11, 2010 by Hae-Jun Baek and Mi-Sook Min; ten specimens (CGRB-15446���455; field numbers: MMS 1989���93, 1997, 2114���17; 8 males, 1 female) from the environs of Wangji-dong, Suncheon-si, Jeollanam-dp, South Korea, collected on March, 11 and April 21, 2010 by Hae-Jun Baek and Mi-Sook Min; and thirty four specimens (CGRB-15502-535; field numbers: AR10���15, 17-19, 21-25, 27���30, 71���83, 85���87; 26 males, 8 females) from Goheung-gun, collected in March 2009 by Jae Young Song and Min Ho Chang. Diagnosis. The species is assigned to the genus Hynobius based on the following character states considered diagnostic for the genus: (1) lungs present; (2) digits in adults lack cornified claw-like structures; (3) dermal flaps on posterior edges of hindlimbs in adults absent; (4) tail relatively short, shorter than body, and distinctly flattened for most of its length; (5) vomerine teeth arranged in a distinctly curved series with inner branches notably longer than outer branches and located posterior to the level of choanae; (6) frontal fontanelle between frontals and parietals absent; (7) light, broad dorsal stripe absent; (8) fifth toe well-developed (Dunn 1923; Sato 1943; Zhao et al. 1988; Adler & Zhao 1990; Fei et al. 2006). In external morphology the new species most closely resembles the other Korean species of Hynobius, but is notably smaller. Hynobius unisacculus sp. nov. is distinguished from its congeners by a combination of the following morphological attributes: (1) comparatively small-size (adult SVL up to 61 mm; range 38.3���60.3 mm in males and 37.5���59.9 mm in females) within the lentic-breeding Hynobius (breeding in shallow still waters, such as ditches or paddy-fields); (2) relatively slender short limbs; large gap (gap of -3.0 to -1.5 costal folds in males and -3.5 to - 1.5 in females) always separating tips of fore- and hindlimbs adpressed on body; (3) comparatively short and flattened tail (TL/ SVL ratio in adult males varying from 0.54 to 0.98, in adult females from 0.55 to 0.89), with a low dorsal fin along the posteriormost one-third of its length; (4) usually 11 (occasionally 12) costal grooves (excluding axillary groove); with 13 (occasionally 12) trunk vertebrae; (5) dark brown dorsum in adults, with indistinct bronze or dark copper spots, lighter greyish-white or pinkish belly; (6) well developed fifth toe; (7) comparatively shallow vomerine tooth series with 13���23 vomerine teeth; (8) small, pigmented ova, located in one, occasionally two, string(s) in small, curved egg sac with folded envelope, lacking distinct mucous stalks or whiptail-like structure on both ends; in the wild usually laid as single egg sacs; the new species is also markedly different from all studied congeners, including other Korean Hynobius, in its sequences of three mitochondrial DNA genes (12S rRNA, COI, cyt b). Description of holotype. An adult male, in a good state of preservation, fixed in and preserved in 70% ethanol, with an SVL of 50.8 mm (measured on the preserved specimen) (see Figs. 3, 4). Trunk. Body elongated, slender and cylindrical (Fig. 3, A, B); chest comparatively narrow: the CW/ SVL ratio 0.13. The skin of the dorsum and venter is smooth, slimy; diffuse microscopic glands scattered all over the body. Mid-dorsal groove weakly developed on the dorsum, extending from the basis of the head to the base of the tail. Costal grooves well developed, 11 grooves visible on each side of the body (excluding the axillary groove), 11 grooves visible from ventral side; ventral abdominal vein visible through translucent skin on the belly (Fig. 3, B). Cloaca. Cloaca noticeably swollen and protuberant in ventral and lateral views (Fig. 3, E). Vent longitudinal, elongate Y-shaped with swollen edges and well-developed protuberance on anterior edge of vent (Fig. 3, E). Tail. Tail comparatively short, noticeably shorter than the body, ratio of tail length (TL) to body length (SVL) 0.77. Tail laterally compressed for most of its��� length; anterior one-fifth of tail length subcilindrical to oval in transverse section; noticeably flattened for final two-fifths of its length, with a low dorsal tail fin. Tail width / height ratio at the middle of its length (MTW/MTH) is 0.73; tail fin highest point located on the posterior one-third of its length. Final fifth of tail length tapers slightly; tail tip acute. Tail widest near its base. Extremities. Limbs slender and rather short, hindlimbs slightly longer and more robust than forelimbs (FLL/ HLL ratio 0.84) (Fig. 3); when forelimb and hind limb adpressed (towards each other) against trunk, digit tips do not meet, separated by a gap equal to three costal segments (folds); forelimb length (FLL) to groin-axilla distance (GA) ratio is 0.36; hind limb length (HLL) to groin-axilla distance (GA) ratio is 0.43. Palmar and tarsal tubercles on palms and feet not developed; digital webbing lacking; digits convex in transverse section. Four fingers and five toes present; finger length in order of increasing length: IV Head. Head oval, slightly depressed, comparatively small (HL/ SVL ratio 0.25), notably longer than wide: head length (HL) / head width (HW) ratio 1.64; head comparatively narrow; head basis not distinct from short neck (Fig. 4). Tongue large, convex-elliptical, adhering to floor of mouth with free lateral margins. Snout wide and rather short, snout length (OR) / head length (HL) ratio 0.38; snout tip rounded in dorsal view (Fig. 4, A), bluntly rounded in lateral view (Fig. 4, C). Nares small, rounded, with lateral orientation, not protuberant, quite widely separated (IN/HL ratio 0.24), equidistant from eye corner and snout tip (ON/OR ratio 0.49). Eyes comparatively small (EL/HL ratio 0.21), distinctly protuberant in lateral view (Fig. 4, C); slightly protuberant in dorsal view (Fig. 4, A), eye diameter is notably less than snout length and less than the distance between external nares: eye length (EL) to snout length (OR) ratio 0.71; eye length (EL) / internarial distance (IN) ratio 0.84. Eyes widely spaced, interorbital distance relatively great (IO/HL ratio 0.24; EL/ IC ratio 0.57). Eyelid present, well developed; labial folds absent; gular fold distinct (Fig. 3, B; Fig. 4, B). Parotid area slightly swollen, but distinct parotid glands absent. Subparotidal protuberance very distinct, swollen, ovate, extending from angle of jaw to gular fold, separated from the parotid area by a deep longitudinal subparotidal groove (Fig. 4, C). Subparotidal groove begins above jaw angle and extends posteriorly, curving ventrally at head basis and intersecting with gular fold at its end. Longitudinal postorbital groove distinct and running from posterior corner of eye toward area located slightly dorsal to angle of jaw. Postorbital groove slightly shorter than eye length, not reaching angle of mouth, terminating ca. 1.0 mm above it, where it joins subparotidal groove and short transverse supraquadratal groove, running ventrally toward mouth angle (Fig. 4, C). Dorsal surface of head with two lines of well developed neuromasts extending posteriorly from the snout (area between external nares) to anterior corners of eyes and then further posteriorly along the orbit margins slightly curving laterally posteriorly than the eyes (Fig. 4, A) and approaching postorbital grooves on the lateral sides of head (Fig. 4, C); over 25 neuromasts discernable in each line. Vomerine teeth. Vomerine teeth in two small, wide, obliquely arched series (VTS), nearly touching at midline, and forming a shallow and longer ������-shaped figure without noticeable gap between branches; outer branch of vomerine tooth series (VTS) short and slightly curved, reaching the level of the outer edge of the internal nares (Fig. 5); VTS inner branches almost straight, only at the very end slightly curved anteriorly. Right VTS with 18 vomerine teeth, left with 17 teeth. Left and right vomerine tooth series in contact with each other with no gap between the medial ends of the inner branches of the tooth series. Branches of outer tooth series less than half the lengths of inner series branches. Vomerine tooth series much wider than long; VTL/ VTW ratio 0.66. Upper jaw with 75 maxillary and premaxillary teeth. Measurements and counts of the holotype. All measurements in mm: SVL: 50.80; TL: 38.96; GA: 29.59; FLL: 10.78; HLL: 12.81; HL: 12.59; HW: 7.68; EL: 2.59; IN: 3.07; ON: 1.78; IO: 3.03; IC: 4.52; OR: 3.64; CW: 6.61; OR: 4.75; 1-FL: 0.84; 2-FL: 2.10; 3-FL: 1.71; 4-FL: 0.75; 1-TL: 1.15; 2-TL: 2.20; 3-TL: 3.17; 4-TL: 2.54; 5- TL: 0.76; MTH: 5.34; MTW: 3.92; MAXTH: 5.67; VTL: 2.15; VTW: 3.28. Counts: VTN (total): 35; VTN (right series): 18; VTN (left series): 17; UJTN: 72; CG: 11 (11 visible from ventral side; 12 if include axillary fold); CGBL: -3.0; TGN: 6. Color of the holotype in life. In life dorsal background dark brown with unclear markings varying in color from tan to dark copper (Fig. 6). Dorsal surfaces of trunk, head and limbs covered with small coppery spots that tend to fuse with each other, becoming larger and lightening to bronze on the dorsal surface of tail. Lateral sides of body dark purplish-grey lightening slightly to purplish or pinkish color ventrally. Posterior half of lateral sides of tail with small, sparse, bluish-white speckling. Throat, chest, ventral surfaces of limbs and anterior third of tail length pinkish; bluish ventral abdominal vein visible through translucent skin of belly. Cloacal area pinkish with indistinct dark markings. Posterior two thirds of tail length brownish ventrally. Iris dark bronze with black markings. Color of the holotype in preservative. After six years in alcohol, the coloration of the holotype is lighter; with dark dorsal background faded to light brown or brownish-grey (Fig. 3); pinkish coloration of ventral surfaces of body disappear and turned yellowish-grey. General coloration pattern without significant change; dark dots of melanophores even more discernible than in life; dorsal surfaces of head, trunk and tail with small dark spots and blotches. Variation. All individuals in the type series appear generally similar in morphology and body proportions; variation of the type series in morphometric characters is shown in Table 3. All individuals were examined after they had been preserved for 12 months in alcohol. There are 11���12 costal grooves (excluding the axillary groove); no statistically significant differences in number of costal grooves were detected. In all specimens examined limbs and digits are relatively short and adpressed limbs never overlap, leaving two to four intercostal folds uncovered; females tend to have slightly longer bodies and shorter limbs than males. Eyes are comparatively small (horizontal diameter 2.2���3.0 mm) and moderately protuberant. In all specimens all five toes are well-developed. No autotomy has been observed in the new species. Some specimens have very short tails (TL Coloration. The dorsal color varies from olive to various shades of dark brown or tan. Some specimens have yellowish-brown, bronze or dark-copper speckles and spots from head to tail, while other specimens show no such speckles. In specimens with light speckles or spots on the dorsum, the light markings usually tend to fuse together on the dorsal and lateral sides of the tail, but never form a contrasting light band. Sides of the trunk and belly are always lighter than the dorsum: coloration can vary from pinkish beige to grey. Some specimens show the presence of light silvery-grey or whitish-blue speckles on the lateral sides of tail, trunk and head; such speckles are more abundant on semi-adult and juvenile specimens than on adults. Secondary sexual characteristics. During the breeding period, males have a noticeably swollen cloacal area, with longitudinal vent slit, bifurcating anteriorly in a Y-shaped figure, with two short grooves running from the Yshaped slit in postero-lateral direction; the anterior corner of the vent has a prominent protuberance (Fig. 3, E). The cloacal area of females is less swollen and the vent is a simple longitudinal slit. Males usually have a higher tail-fin. Reproduction. Breeding occurs between late February and late March; animals appear to leave water during April, after reproduction. H. unisacculus sp. nov. reproduces in still waters, such as like road-side ditches (Fig. 7, A), puddles and trenches on rice paddies (Fig. 7, B). During the day time, adult animals usually hide among dead leaves on the waterbody used for breeding. Eggs and clutch. Although information on the ecology of H. unisacculus sp. nov. is limited, to date females have not been observed attaching their egg sacs to substrate. All species of Hynobiidae, including H. unisacculus sp. nov., are known to lay eggs in a pair of mucous sacs, deposited one per female���s oviduct during spawning; egg sacs are usually within a strong envelope (Dunn 1923, Sato 1943). The paired sacs as a rule are joined together at the distal end from which two mucous stalks arise; each stalk is used to attach a pair of egg sacs to the substrate (such as leaves, branches or stones); this mucous stalk is very weak and easily breaks during the egg-laying process. Perhaps this is the reason that in the wild we have only observed single egg sacs of H. unisacculus sp. nov. freely deposited in the waterbody, without a gelatinous stalk and not attached to any substrate (Fig. 8, A, B). This peculiar reproduction is not typical for other lentic-breeding Hynobius species (Dunn 1923, Sato 1943, Sparreboom 2014), and was noticed by Song and Koo (2010) who reported on this unusual reproductive biology (they indicated the gelatinous stalk as a ���whiptail-like structure���). However, many details of the reproductive biology of H. unisacculus sp. nov. remain unclear and further studies are necessary to shed light on this question. Egg sacs of the new species are comparatively small (Fig. 8, C) and curved forming a C-shaped or O-shaped figure, with a transparent envelope, covered by numerous irregular folds (Fig. 8, A, C). Eggs are pigmented, located in two rows or in a single row within the egg-sac (Fig. 8, C). Variation in the morphology of egg sacs in the H. leechii complex in southern Korea is discussed in detail by Song and Koo (2010); their study also includes data on the egg sacs of H. unisacculus sp. nov. (as Narodo and Boseong populations of H. leechii). According to Song and Koo (2010), clutch size (CS) in the new species varies from 17 to 88 eggs; median values were 34.9 �� 9.0 (N = 101) for the Narodo and 47.1��15.4 (N = 39) in the Boseong population. H. unisacculus sp. nov. has comparatively small egg sacs; egg sac length (ESL) is less than 150 mm: 130.5 �� 20.9 mm (86 mm ��� 209 mm) in the Narodo and 134.1 �� 28.8 mm (85 mm ��� 187 mm) in the Boseong populations. Egg sac width (ESW) varies from 13.9 �� 1.5 mm (10 mm ��� 18 mm) in the Narodo to 12.9 �� 1.8 mm (10 mm ��� 17 mm) in the Boseong populations. The ESL/ESW ratio for H. unisacculus sp. nov. (mean 9.1��1.5 for the Narodo and 9.9��1.8 for the Boseong populations) was significantly different from several populations of H. leechii (11 H. quelpaertensis (ESL/ ESW>14) (Song & Koo 2010). Larval morphology and metamorphosis. To date we lack any data on the development and morphology of the larval stage of the new species. Metamorphosis takes place during the second half of summer. Etymology. The specific name ��� unisacculus ��� is a noun in masculine gender, used in apposition, based on the Latin words ��� unicus ��� (single) and ��� saccus ��� (sac), or, more precisely, ��� sacculus ��� (small sac), meaning ���a single small sac���. The species name refers to the unusual egg structure and breeding biology of the new species. The suggested vernacular name in English is ��� Korean small salamander ���; the suggested common name in Korean: ��� Kkoma��� Dorongnyong ���. Distribution, habitats and natural history. To date, the new species has been found in four localities within the southeastern part of Jeollanam-do, South Korea: Goheung, Suncheon, Bosoeung and Yeosu areas (Fig. 9, localities 1���6). Specimens from these localities were used in the genetic study of Baek et al. (2011a, 2011b) and their taxonomic assignation to Hynobius unisacculus sp. nov. was confirmed by mtDNA sequence analysis. However, Chang et al. (2011) reported several other populations of the H. leechii species complex on adjacent offshore islands along the southeastern coast of Jeollanam-do (Fig. 9, Published as part of Min, Mi-Sook, Baek, Hae-Jun, Song, Jae-Young, Chang, Min Ho & Poyarkov Jr, Nikolay A., 2016, A new species of salamander of the genus Hynobius (Amphibia, Caudata, Hynobiidae) from South Korea, pp. 475-503 in Zootaxa 4169 (3) on pages 486-498, DOI: 10.11646/zootaxa.4169.3.4, http://zenodo.org/record/264812, {"references":["Sato, I. (1943) Monograph of the Tailed Batrachians of Japan [= Nippon-san yubirui sosetsu]. Nippon Publ. Co., Osaka, 520 pp. [in Japanese]","Chang, M. - H., Koo, K. - S. & Song, J. - Y. (2011) The list of amphibian species in 66 islands in Korea. Korean Journal of Herpetology, 3, 19 - 24.","Kim, J. - B., Min, M. - S. & Matsui, M. (2003) A new species of lentic breeding Korean salamander of the genus Hynobius (Amphibia, Urodela). 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