Ichthyophis chaloensis, Geissler & Poyarkov & Grismer & Nguyen & An & Neang & Kupfer & Ziegler & Böhme & Müller, 2015

Geissler, Peter, Poyarkov, Nikolay A., Grismer, Lee, Nguyen, Truong Q., An, Hang T., Neang, Thy, Kupfer, Alexander, Ziegler, Thomas, Böhme, Wolfgang & Müller, Hendrik, 2015, New Ichthyophis species from Indochina (Gymnophiona, Ichthyophiidae): 1. The unstriped forms with descriptions of three new species and the redescriptions of I. acuminatus Taylor, 1960, I. youngorum Taylor, 1960 and I. laosensis Taylor, 1969, Organisms Diversity & Evolution (New York, N. Y.) 15 (1), pp. 143-174 : 162-164

Ichthyophis chaloensis sp. nov.

Holotype Metamorphosed female ( IEBR A.2011.16, Fig. 11 ), collected at night on 16 September 2011 by H. T. An and T. Q. Nguyen in the forest near Cha Lo Village (17° 42′ 11.7″ N 105° 46′ 59.3″ E; elevation, 621 m), Hoa Son Commune , Minh Hoa District (extension area of Phong Nha – Ke Bang National Park), Quang Binh Province, Vietnam.

Diagnosis A species of Ichthyophis without a lateral yellow stripe; snout elongated, acuminate and highly projecting (SP/ HL=0.14); TN/ ET =2.2; premaxillary and maxillary teeth 37, vomeropalatine teeth 54, dentary teeth 26, inner mandibular teeth 11; inner mandibular tooth row shorter than dentary row; tail acuminate, ending in a nipple-like cap; total annuli 344 (dorsal count), encircling venter by forming an angle pointing tailwards, three interupted by cloacal disc, five posterior to cloacal disc; cloacal disc oval in shape; vertebrae 110; scales present solely on posterior half of body, in one row per annulus (dorsolaterally). The new species differs from all other known unstriped congeners in the following characters: from I. acuminatus by a smaller eye (HL/ ED =31.3 vs. 20.9) and a larger snout projection (SP/ HL=0.14 vs. 0.01–0.05); from I. billitonensis by more inner mandibular teeth (11 vs. 2); from I. bombayensis by the absence of scales in the anterior half of body; from I. cardamomenis sp. nov. by a smaller eye (HL/ ED =31.3 vs. 11.5–13.2) and a larger snout projection (SP/HL = 0.14 vs. 0.04–0.09); from I. catlocensis sp. nov. by a smaller eye (HL/ ED =31.3 vs. 14.6) and a larger snout projection (SP/HL=0.14 vs. 0.07); from I. dulitensis by the absence of scales in the anterior half of body; from I. glandulosus in having more annuli (344 vs. 273–286); from I. javanicus by a more elongated snout (HL/ ES =1.95 vs. 2.68) and a minute, indistinct eye (vs. “eyes very distinct” ( Taylor 1960)); from I. lakimi by a smaller eye (HL/ ED =31.3 vs. 4.5); from I. laosensis by a smaller eye (HL/ ED =31.3 vs. 10.9) and a larger snout projection (SP/HL=0.14 vs. 0.06); from I. larutensis by the presence of inner mandibular teeth; from I. monochrous by more annuli (344 vs. 247); from I. orthoplicatus by having more annuli (344 vs. 205–291); from I. sikkimensis by more annuli (344 vs. 276–292); from I. singaporensis by the absence of scales on the anterior half of body; from I. sumatranus by the absence of scales on the anterior half of body; from I. weberi by the presence of inner mandibular teeth; from I. youngorum a larger snout projection (SP/HL=0.14 vs. 0.01 in metamorphosed specimens).

Description of holotype Selected morphological and meristic data are given in Table 4. Condition of the preserved specimen: incisions in both corners of mouth; two ventral incisions, first (26 mm in length) about 40 mm posterior to snout tip and second over about 60 mm anterior to cloacal disc; and few scale pockets opened dorsolaterally; paravertebral skin somewhat parched during fixation, resulting in brownish discoloration of the affected areas ( Fig. 11 ).

Head ( Fig. 11 ) flattened dorsoventrally; in dorsal view, head broadened between first collar and corner of mouth, anterior to corner of mouth distinctly narrowing towards tentacle; snout anterior to tentacles elongated and acuminate; in lateral view, head barely tapered between collar region and nares; nares very close to tip of snout; snout dropping almost vertically anterior to naris; lips straight edged; corner of mouth somewhat closer to throat than to top of head; mouth subterminal, snout highly projecting; in ventral view gular region flattened, with a median groove, starting at level of tentacles, fading on second collar; eyes minute, covered by unpigmented skin, rounded, lens forming a dark-grey central disc, not elevated above adjacent skin; in lateral view, eyes much closer to top of head than to upper lip; tentacular aperture 2.2 times closer to the eye than to naris, almost reaching the edge of the upper lip, about the size of the eyes; tentacular sheaths elevated above adjacent skin, visible in dorsal, lateral and ventral view; in preservative, tentacles slightly protruding from the tentacular apertures; nares oval in shape, closer to top of head than to upper lip, barely visible in dorsal view, not visible in ventral view; teeth ( Fig. 5c ) small, strongly recurved and bicuspid; 37 premaxillary-maxillary, 54 vomeropalatine, 26 dentary, and 11 inner mandibular teeth; teeth in premaxillary-maxillary and dentary series larger than teeth in vomeropalatine and inner mandibular series; length of inner mandibular tooth row only slightly shorter than vomeropalatine row; length of inner mandibular tooth row about half of dentary row; palate only slightly arced; choanae oval, narrow and elongated, somewhat posterior to tentacles; tongue triangular with an acuminate tip; first collar as wide as, but somewhat deeper than, head; second collar gradually narrowing towards body; collar grooves only distinct on ventral skin, fading laterally, hardly detectable in lateral or dorsal view; no dorsal transverse groove on second collar; anterior as well as posterior border of collar region not well differentiated, only bordered by the anteriormost annular grooves of body; in ventral view, second collar slightly longer than first; anteriormost five annuli incomplete ventrally; following grooves (over about 160 mm of trunk length) encircle venter by forming an angle pointing towards tail; from about 20 mm anterior to cloacal disc, grooves cross venter in a straight line; slight median depression present on whole venter; annular grooves cross dorsum by forming a rounded angle towards head; total annuli 344/342 (dorsal count/ventral count); vertebrae 110; longitudinal cloacal slit situated in a oval cloacal disc, interrupting three annuli; cloaca surrounded by 7/7 (right/left) denticulations ( Fig. 6c ); tail bearing five annuli, grooves not complete ventrally; tail terminating in a distinct nipple-like cap; scales present only in the posterior half of body, in one row per scale pocket (counted dorsolaterally); scales oval.

Coloration In preservative: dark grey on dorsum and somewhat lighter ventrally; cloacal disc white; tale cap white; eyes, tentancles and nares encircled by a narrow white margin (see Fig. 11 ). In life: dark chestnut-brown on dorsum and flanks; somewhat lighter on belly; annular grooves as well as head light brown; collars distinctively darker; and nares and tentacle sheaths encircled by a whitish margin.

Etymology The specific epithet is in reference to the type locality of the forest near Cha Lo Village, Hoa Son Commune, Minh Hoa District, Quang Binh Province, Central Vietnam.

Natural history The type specimen was found at 8: 30 p. m. under leaf litter on the bank of a small rocky stream. The surrounding habitat was mixed secondary lowland forest of hardwood, shrub, and liane.

Distribution To date only known from the type locality. Ichthyophis cf. bannanicus was found in close geographical proximity to the unicolored I. chaloensis sp. nov., though cases of sympatry of these two species are not known yet.

Conservation status So far only one specimen of I. chaloensis sp. nov. has been recorded within the extension area of Phong Nha–Ke Bang National Park in central Vietnam. According to the IUCN (2012) criteria, we recommend the species to be considered as Data Deficient. Future research is urgently needed to gather data on the actual distribution and population size of I. chaloensis sp. nov (see Fig. 12 ).

Figures

Fig. 11 Holotype (IEBR A.2011.15) of Ichthyophis chaloensis sp. nov.in preservative (TL, 215.7 mm). Photographs by PG

Fig. 5 a–f Jaws of the holotype of (depicted characters are also present in the respectively investigated paratype specimens): a Ichthyophis cardamomensis sp. nov. (LSUHC 9335), b Ichthyophis catlocensis sp. nov. (ZFMK 88976), c Ichthyophis chaloensis sp. nov. (IEBR A.2011.16), d Ichthyophis laosensis (MNHN 1928.95), e Ichthyophis acuminatus (AMNH A20875), and f Ichthyophis youngorum (FMNH 189250). Drawings by PG

Fig. 6 a–f Tail region (in ventral view) of the holotype specimens of: a Ichthyophis cardamomensis sp. nov. (LSUHC 9335), b Ichthyophis catlocensis sp. nov. (ZFMK 88976), c Ichthyophis chaloensis sp. nov. (IEBR A.2011.16), d Ichthyophis laosensis (MNHN 1928.95), e Ichthyophis acuminatus (AMNH A20875), and f Ichthyophis youngorum (FMNH 189250). Drawings by PG

Fig. 12 Holotype (IEBR A.2011.15) of Ichthyophis chaloensis sp. nov. in life (TL, 215.7 mm) from Cha Lo Village in the extension area of Phong Nha-Ke Bang National Park, Minh Hoa District, Quang Binh Province, Vietnam. Photograph by NQT