Ichthyophis laosensis Taylor, 1969

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 : 164-166

Ichthyophis laosensis Taylor, 1969

I. laosensis Taylor, 1969 , Univ. Kansas Sci. Bull., 48: 292. Holotype Adult female (MNHN 1928.95, Fig. 13 ), collected in “Haute Laos “(= Upper Laos), collector unknown ( Taylor 1969).

Diagnosis A species of Ichthyophis without a lateral yellow stripe; snout blunt and rounded (SP/HL=0.06); TN/ET=2.7; premaxillary and maxillary teeth 33, vomeropalatine teeth 36, dentary teeth 35, inner mandibular teeth 30; inner mandibular tooth row shorter than dentary row; tail ending in a large blunt cap; total annuli 346 (dorsal count), encircling venter by forming an angle pointing tailwards, though somewhat indistinct medially along the whole venter; three annuli interrupted by cloacal disc, two posterior to cloacal disc; cloacal disc round; vertebrae 112; scales present in two to three rows per annulus (dorsolaterally) over the whole length of body.

The species differs from all other known unstriped congeners in the following characters: from I. acuminatus by the presence of scales on the anterior half of body; from I. billitonensis by more inner mandibular teeth (30 vs. 2); from I. bombayensis by more inner mandibular teeth (in specimens of equal or larger size) (IM= 30 vs. 8–18); from I. cardamomensis sp. nov. by the presence of scales on the anterior half of body; from I. catlocensis sp. nov. by the eye being more distant from the eye than from naris (TN/ET= 2.7 vs. 4.5); from I. chaloensis sp. nov. by a larger eye size (HL/ ED=10.9 vs. 31.3) and a smaller snout projection (SP/HL=0.06 vs. 0.14); from I. dulitensis by fewer scale rows per pocket (1 vs. 4–5); from I. glandulosus in having more annuli (346 vs. 273– 286); from I. javanicus by the presence of scales on the anterior half of body; from I. lakimi by the presence of scales on the anterior half of body; from I. larutensis by the presence of inner mandibular teeth; from I. monochrous by more annuli (346 vs. 247); from I. orthoplicatus by more annuli (346 vs. 205–291); from I. sikkimensis by more annuli (346 vs. 276–292); from I. singaporensis by more annuli (346 vs. 267); from I. sumatranus by more annuli (346 vs. 315–329); from I. weberi by the presence of inner mandibular teeth; from I. youngorum by the presence of scales on the anterior half of body.

Description of holotype Selected morphological and meristic data are given in Table 4. Condition of the preserved specimen: both jaw angles broken; large T-shaped cut in skin on dorsal side of head; skull as well as parts of the skin around the snout area are missing; three ventral incisions, first (44 mm in length) at midbody, second (60 mm in length) about 12 mm posterior to the first, and third (42 mm in length) lateral and anterior to vent disc; several scale pockets opened dorsolaterally; and beige in color.

Head (see Fig. 13 ) probably flattened dorsoventrally; in dorsal view, head narrows slightly between first collar and corner of mouth, anterior to corners of mouth the head is distinctly narrowing towards tentacle; snout anterior to tentacles bluntly rounded; in lateral view, head tapers between collar region and nares; nares very close to tip of snout; snout dropping almost vertically anterior to nares; lips straight edged; corner of mouth somewhat closer to bottom of head than to top of head; mouth terminal, snout barely projecting; in ventral view, gular region flattened, with a distinct median groove, starting at level of tentacles, continuing on first collar; eyes visible through unpigmented skin, rounded, lens forming a dark-grey central disc, not elevated above adjacent skin; in lateral view eyes somewhat closer to top of head than to upper lip; tentacular aperture 2.7 times closer to the eye than to naris, almost reaching the edge of the upper lip, smaller than naris; tentacular sheaths elevated from adjacent skin, visible only in dorsal view; in preservative, tentacles slightly protruding from tentacular aperture; nares oval in shape, closer to top of head than to upper lip, visible in dorsal view, not visible in ventral view; teeth ( Fig. 5d ) small, strongly recurved and bicuspid; 33 premaxillary-maxillary, 36 vomeropalatine, 35 dentary, and 30 inner mandibular teeth; teeth in premaxillary-maxillary and dentary series slightly larger than teeth in vomeropalatine and inner mandibular series; length of vomeropalatine longer than premaxillary-maxillary row; length of inner mandibular tooth row about three thirds of dentary row; palate only slightly arced, choanae oval, slightly elongated; tongue triangular with a blunt tip; first collar wider and deeper than head; second collar gradually narrowing towards trunk; collar grooves only distinct on ventral and lateral skin, vanishing dorsally; in ventral view, anterior as well as posterior border of collar distinct; second collar slightly longer than first; no dorsal transverse groove on second collar; anteriormost six annuli not encircling the belly; following grooves encircle venter by forming an angle pointing towards tail; on about 40 mm anterior to cloacal disc, grooves cross venter in a straight line; on the median portion of venter, grooves are less distinct and less deep than on flanks and dorsum; even double-S shape; total annuli 346/345 (dorsal count/ventral count); vertebrae 112; longitudinal cloacal slit situated in a round cloacal disc, interrupting three annuli; cloaca surrounded by 7/7 (right/left) denticulations ( Fig. 6d ); tail bearing two annuli, grooves not complete ventrally, terminating in a distinct large cap; scales present in one row per scale pocket (counted dorsolaterally) over the whole length of trunk; scales oval in shape.

Differences from the description by Taylor (1969) The following characters measured or counted by us deviate from the data provided by Taylor (1969) (marked with an asterisk): HW=9.7 vs. 12*; AV=3 vs. 2*; TN=4.3 vs. 4.2*; EE=6.2 vs. 7.3*; ES=5.1 vs. 6.3*; UJL=10.8 vs. 9.5; PMM=33 vs. 43*; VP=36 vs. 44*; DE=35 vs. 40*; IM=32 vs. 30*.

Coloration Faded in preservative and now uniformly fawn colored, showing nearly no difference between dorsum and venter ( Fig. 13 ). Presumably much darker in life. There is no indication of a formerly (in life) present lateral stripe

Figures

Fig. 13 Holotype (MNHN 1928.95) of Ichthyophis laosensis in preservative (TL, 318.0 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