Hydrus piscator Schneider, 1799

Published, First, 2012, 3473, Zootaxa 3473, pp. 1-60 : 6-8

Hydrus piscator Schneider, 1799

Hydrus piscator Schneider, 1799: 247 ; based on Russell (1796: 38, pl. 33, “Neeli Koea”).—Type locality “ Indiae orientalis ”, namely Eastern India; here restricted by geographic inference to the northern coastal areas of Andhra Pradesh State, eastern India; see below.—Onomatophore. Holotype, rediscovered and first cited in the present work: BMNH 1904.7.27.32 ( Fig. 1) (specimen depicted by Russell, 1796: pl. 33); see below.

Status. A valid taxon, as Xenochrophis piscator , including all populations sharing the morphological characters defined subsequently.

Comments. Russell (1799) did not mention a locality for his specimen of ‘Neeli Koea’. However, this vernacular name, also transcribed as a Nihli Koeahat by Schneider (1799) or, now, Neeti Koela (I. Das, in litt., January 2009) is in Telugu. This language is spoken only in the northern areas of the former Coast of Coromandel, now the northern coastal areas of Andhra Pradesh State (I. Das, in litt., January 2009). Furthermore, Russell was stationed in “Vizagapatam”, now Vishakhapatnam, in northern Andhra Pradesh State. Thus, we restrict the original type-locality of Hydrus piscator Schneider, 1799 to the lowlands along the northern Coast of Coromandel, namely the northern coastal areas of Andhra Pradesh State, eastern India.

No collection number has ever been applied to the holotype of Hydrus piscator , namely the specimen depicted by Russell (1796). However, thanks to C. J. McCarthy (BMNH), we were able to examine a collection of 97 skilfully prepared skins deposited by Russell or a successor in the BMNH collections. These skins, with data presumably hand-written by Russell himself, are stored in a wooden case. Collection numbers were given to all of them, probably by Boulenger. All skins are in surprisingly good condition. Especially noteworthy is the fact that their colour is still vivid. These skins are the specimens depicted by Russell; their nomenclatural importance will be discussed elsewhere (Vogel, David & McCarthy, unpublished data.). Thanks to the quality of Russell’s plate depicting the “Neeli Koea” and to the limited number of skins of Hydrus piscator in this collection, it was easy to identify the actual specimen which he had illustrated and hence is the preserved holotype of H. piscator . Because Russell gave a very precise description of the depicted specimen, which was obviously made from a fresh specimen, and due to the limited availability of Russell’s work, we present the description of the holotype ( Fig. 1), verbatim from Russell (1796: 38):

“Abdominal scuta:152

Sub-caudal Squamae:80

Called by the natives Neeli Koea

The head broader than the neck, broad-ovate, depressed; compressed on the sides towards the rostrum; covered with various laminae; the first pair, triagonal, small, between the nostrils; the next pair, quadrangular, somewhat larger; the shield-form lamina, between the eyes, is pointed; the lateral, sub-oval; the semi-cordate pair are very large; and on each side is an oblong, narrow,

lamina: besides some others which are smaller.

The mouth, wide; the lower jaw shorter than the upper. The teeth numerous, small, sharp, reflex; a marginal, and two palatal rows in the upper jaw.

The eyes lateral, very forward, large, orbicular. The nostrils close to the point of the rostrum, small, open

The trunk, round, clumsy shaped; the scales on the back, oval, carinated, imbricate; on the sides, not carinated, and two rows next to the scute, larger roundish, smooth. The length, two feet nine inches and a half; the circumference, three inches and a half.

The tail slightly carinated, tapers very gradually till within four inches of its sharp point: length eleven inches.

The colour; the head darker than the rest; two unequal, black, streaks, behind each eye, with a yellow spot between them. The neck, trunk, and tail, of a yellowish brown, with numerous round, black, spots, joined by narrow, black, fillets, regularly disposed in oblique rows; a few scales of paler yellow being interspersed. On the tail the spots are not joined, and towards the point disappear. The scuta and squamae are of yellowish white. ”

The examination of the skin rediscovered in the BMNH collection allows us to add a few characters not mentioned by Russell: On the left side, 9 supralabials, SL 4–5 entering orbit; 2 elongated anterior temporals, the lower largest, 2 temporals in the second row, one in the third row; 1 loreal not touching the eye; 1 preocular, 3 postoculars. We do not repeat here the description of Schneider (1799). In Latin, it is quite extensive and is based on Russell’s plate.