Kottelatlimia hipporhynchos, Kottelat & Tan, 2008

Kottelat, Maurice & Tan, Heok Hui, 2008, Kottelatlimia hipporhynchos, a new species of loach from southern Borneo (Teleostei: Cobitidae), Zootaxa 1967, pp. 63-72 : 64-70

Kottelatlimia hipporhynchos , new species

( Fig. 1)

Holotype. MZB 10977, 45.5 mm SL; Borneo: Kalimantan Tengah: Kahayan drainage, blackwater stream at km 80 on road from Palangka Raya to Tumbang Telakian (35 km after turn-off at km 45 on road from Palangka Raya to Kasongan); 1°37.324’S 113°37.569’E; H. H. Tan & M. Kottelat, 8 Mar 2008.

Paratypes. MZB 10988, 4 , 39.3–45.7 mm SL ; ZRC 51423, 13 , 38.8–52.1 mm SL; CMK 20421, 13, 37.7–45.5 mm SL; same data as holotype . — ZRC 51199, 3 , 26.9–45.7 mm SL; Borneo: Kalimantan Tengah: Kahayan drainage, blackwater stream at km 46 on road from Palangka Raya to Kasongan ; 1°56.495’S 113°39.322’E; H. H. Tan et al., 21 Sep 2007 . — ZRC 51424, 4 , 22.4–37.8 mm SL; CMK 20373, 3, 23.1–35.2 mm SL; Borneo: Kalimantan Tengah: Kahayan drainage, Tangkiling , blackwater stream after km 46 on road from Palangka Raya to Kasongan ; 1°56.476’S 113°39.218’E; H. H. Tan & M. Kottelat, 5 Mar 2008 . — ZRC 51200, 3 , 35.7–36.3 mm SL; Borneo: Kalimantan Tengah: Kahayan drainage, Sungei Rijak , km 84 along road from Palangka Raya to Telakin ; 1°37.319’S 113°37.560’E; H. H. Tan et al., 18 Sep 2007 . — ZRC 51425, 2 , 37.1–47.4 mm SL; Borneo: Kalimantan Tengah: Kahayan drainage, Bukit Gelaga , stream at ca. 15 km on road turning off road from Palangka Raya to Bargugus ; 1°53.001'S 113°57.367'E; H. H. Tan & M. Kottelat, 7 Mar 2008 . — ZRC 51201, 2 , 32.4–33.6 mm SL; Borneo: Kalimantan Tengah: Plantalang Hulu , 02°01'40"S 112°59'48"E ; T. Idei, 2004. — CMK 16762, 1, 52.3 mm SL; Borneo: Kalimantan Tengah: Kapuas basin: 15 km east of Buntok ; T. Idei , 13 Sep 2000 .

Diagnosis. Kottelatlimia hipporhynchos is distinguished from congeners by the extreme development of papillae on all mouth parts (lips, barbels, lobes), including very long papillae along the anterior edge of the main digitation of the median lobe of the lower lip ( Fig. 2a) (vs. smooth mouth parts, no papillae along edge of main digitation; Fig. 2b). Further, in males, K. hipporhynchos is distinguished from K. pristes by the posterior projections of the upper hemitrichium of the first branched pectoral-fin ray being broad, contiguous and forming a blade-like structure ( Fig. 3a). In K. pristes , these projections (except the proximal ones) are pointed and directed backwards, spine-like, not contiguous, appearing as a saw-like structure ( Fig. 3c). In K. katik , the projections of the upper hemitrichium of the first branched pectoral-fin ray are narrow and form 6–7 fine serrae.

Description. Body shape and general appearance are shown in Figure 1. Morphometric data are given in Table 1.

Ventral profile of head straight; dorsal profile steep from tip of snout to eye, rounded above eye, then straight to caudal-fin base. Eye in posterior half of head. Head naked. Anterior nostril at tip of a slender tube. Suborbital spine bifid; outer prong straight, about half the length of slightly curved, inner one. Upper lip papillated, papillae themselves with smaller papillae. Two pairs of rostral barbels and one pair of maxillary barbels at corner of mouth. Upper lip with a thick lobe between posterior rostral and maxillary barbels, covered by papillae. Maxillary barbel with a flange of skin along its outer edge, for about one third of its length, covered by papillae. Lower lip interrupted medially, each half made of a fleshy lobe along body midline and with a skin fold connecting it to maxillary barbel. Lobe divided into 2 or 3 digitations, posterior one longest (or median one if three digitations); digitations densely covered by papillae; 6–7 large, elongated papillae along anterior edge of median digitation ( Fig. 2a).

Body depth equal between head and dorsal-fin origin; then tapering sharply to base of caudal fin (depth of caudal peduncle 1.7–2.1 times in body depth at dorsal-fin origin). Body almost completely scaled; naked between pectoral-fin bases. Lateral line short, reaching about to mid-length of pectoral fin (pores cannot be counted).

Pectoral fin with 1 simple, 6 branched, and 1 simple rays ( Fig. 2a). First branched ray sexually dimorphic. In male, first branched ray thick, branched only close to tip, with two branches adjacent, without membrane in-between. Upper hemitrichium of first branched ray well separated from and slightly behind lower one, until joining at about midlength. All segments (7–11) of upper hemitrichium proximal to branching with a posterodorsal lamellar projection, with truncate tip. Proximal-most projections adjacent, posterior ones increasingly more separate (but still very close). Projections surrounded by thick tissue and whole structure appearing as a blade, covering most of unbranched part of second branched ray. Pelvic fin with 1 simple, 5 branched, and 1 simple rays; origin under base of 2nd to 3rd branched rays of dorsal fin. Dorsal fin with 3 simple and 8 branched rays (last two articulating on a single pterygiophore). Anal fin with 3 simple and 6 branched rays (last two articulating on a single pterygiophore). Caudal fin slightly emarginate or truncate; with 6+7 branched rays; upper 3–4 rays contiguous, without membrane, along proximal ¼ to ⅓ and lower 3–4 with only narrow membranes.

Vertebrae: 23+11=34 (1), 23+12=35 (1), 24+10=34 (1), 24+11=35 (6), 24+12=36 (1).

Colouration. Body background colour pale yellow, translucent in life. Markings dark brown unless otherwise noted. Upper and median parts of flank with scattered dots; lower part of flank with a few slightly larger dots, more or less aligned. Ten or eleven, narrow saddles along back, anteriormost at nape. A midlateral row of nine or ten very irregular spots between opercle and middle of caudal-fin base, running slightly below midheight of body. Head with a band from eye to about base of anterior rostral barbel and one from eye obliquely backward and downward to anterior edge of opercle. Rest of head with a few scattered melanophores. Parts of head above bands pale grayish brown, below bands pale yellow. Fins hyaline. Dorsal fin with a dark dot straddling base of simple and first branched rays, continuing saddle at dorsal-fin origin; 3 rows of small spots on last simple and all branched rays. Caudal fin with a black spot on base of 5 upper branched rays; 3 irregular vertical rows of spots on rays.

In males, a row of pigments on first branched ray of pectoral fin, corresponding to lines of contact between dorsal projections.

Etymology. From the Greek ïππOς (hippos), horse, and ρDγχiOv (rhunchos), snout, muzzle; a reference to the long, horse-like snout of the large specimens, also reminiscent of the genus Acantopsis (horse-face loaches). A noun in apposition.

Distribution and habitat. Kottelatlimia hipporhynchos is presently known only from southern Borneo (Kalimantan Tengah province), in Kahayan, Sampit and Kapuas basins (note that this is an homonym of the much larger Kapuas of Kalimantan Barat). We have observed it in various habitats, with different substrates (including peat), but it was most abundant in streams with clear tannin-stained water on white sandy bottom. It was observed resting on the sand substrate or diving into it. Kottelatlimia pristes has occasionally been collected at the same localities as K. hipporhynchos , but it does not occupy the same habitat. Kottelatlimia pristes was not observed on sandy substrate but on or inside peat, soil and leave litter.

Remarks. Nalbant (1994) created the genus Kottelatlimia on the basis of the description and discussion of Lepidocephalichthys katik by Kottelat & Lim (1992), without having seen actual specimens. He also published a drawing based on Kottelat & Lim's figure, on which he modified the shape of the mouth, dorsal fin and suborbital spine (his figures 7–9). His representation of the mouth (and corresponding text) modifies and misrepresents the construction of the lower lip and associated parts. The narrow and thin part of the lower lip connecting the maxillary barbel and the median lobe has disappeared and the two digitations on the median lobe, of which the median-most one has one or two elongate papillae, became three barbels. Nalbant based his recognition of a new genus on the following characters: small size, small eye, presence of nasal barbel, simple suborbital spine, head naked, reduced number of vertebrae and saw-like "formation" on first branched pectoral-fin ray in male. Nalbant apparently did not realise that L. pristes of Roberts (1989) also possesses several of these characters, and especially the unique sexually dimorphic condition of the first branched pectoral-fin ray. Kottelat & Whitten (1996) already considered that L. pristes belongs to the same genus as L. katik . The differences between them are related to the miniature size of K. katik . Kottelatlimia katik is a paedomorphic species, which reaches sexual maturity at 13.0 mm SL or smaller (see Kottelat & Lim, 1992). The long barbels and the nasal barbel of adults K. katik are juvenile characters observed in numerous species of Cobitoidei (pers. obs.), the reduction of the number of vertebrae, the simplification of the suborbital spine and the reduction of the projections on the first branched pectoral-fin ray are the kind of reductive traits observed in most miniature or paedomorphic species ( Kottelat et al., 2006; Rüber et al., 2007).

Besides the characters mentioned in the diagnosis, K. hipporhynchos is distinguished from K. pristes by having more vertebrae (34–36, modally 35, vs. 32–34, modally 33), a longer and more slanted snout (44–55 % HL, vs. 34–43), a different body shape (body depth immediately behind head greater than at anal-fin origin, vs. body depth behind head and at anal-fin origin about equal), upper 3–4 principal caudal-fin rays adjacent along proximal 1/4–1/3 (vs. separated, with membranes), a slightly emarginate caudal fin (vs. truncate to rounded), with relatively narrow bars made of pigments on rays (vs. bars broad, about as broad as interspaces, made of pigments on rays and membranes), a plain anal fin (vs. a dark spot at origin and 2 rows of spots on rays), no band or row of dots on cheek below the eye (vs. presence of a faint to distinct, irregular, more or less vertical band or row of dots below the eye), presence of a band between eye and opercle (vs. absence or very short behind eye), and a paler background colour (pale yellow, vs. brown) with much fewer and larger pigments.

The structure of the first branched pectoral-fin ray is similar in K. hipporhynchos and K. pristes , but in K. pristes the two hemitrichia are less separated and the projections are pointed except the proximal ones. Kottelatlimia hipporhynchos is further distinguished from K. katik by having a much larger size (up to 52.1 mm SL, vs. 13.5), the rim of the anterior nostril not modified into a barbel (vs. modified into a nasal barbel), the suborbital spine branched (vs. simple), and more vertebrae (34–36, modally 35, vs. 29).

Species of Acantopsis and Acanthopsoides share with K. hipporhynchos the long snout, the presence of ridges of papillae along the barbels and lips but in the species that we examined, their disposition and organisation vary and differ from the pattern in K. hipporhynchos . In Acantopsis , the lower lip often has several filamentous projections along its posterior edge, which are missing in Kottelatlimia .

Sexual dimorphism in Acantopsis and Neoeucirrhichthys . The taxonomy of Acantopsis is still very confused. Our preliminary observations suggest that a more detailed description of the morphology of the soft parts of the mouth (lips, barbels, etc) and of the modified pectoral-fin rays of males allows the recognition of several additional species. For example, in a large-sized species (up to at least 180 mm SL; ZRC 22004, CMK 8119, from Malaysia: Terengganu: Air Putih), the pectoral fins are straight, the first branched pectoral-fin ray is thicker than the others, its two hemitrichia are separate on about one-third of their length, and the upper one is somewhat displaced posteriorly until the branching point ( Fig. 4a). In another, smaller, species from the same area (up to about 70 mm SL; ZRC 42120, CMK 12073, from Thailand: Sungai Kolok ), the first branched pectoral-fin ray is slightly thicker than the others, its upper hemitrichium only slightly displaced and the tip of the ray and adjacent membranes densely covered by several rows of minute tubercles on the dorsal surface, the simple and second branched rays each have a row of small tubercles ( Fig. 4b) .

Acanthopsoides (which is the sister group of Kottelatlimia according to Šlechtová et al., 2008) does not have the ridges of papillae along the lips and barbels. The first branched pectoral-fin ray is slightly thicker in males, but the upper hemitrichium does not present the modifications observed in Kottelatlimia .

The thickened first branched rays and the projections on the upper hemitrichium in Kottelatlimia might be homologous to the first branched ray and lamina circularis of Cobitis and related genera. But in these genera, the lamina circularis is closer to the body and seems to arise as a single projection from the proximal-most segment of the upper hemitrichium.

Edds & Ng (2007) figured the pectoral fin of the male Neoeucirrhichthys maydelli Bănărescu & Nalbant and provide some information on its morphology. We have examined additional material from Bangladesh and provide the following additional information. In the male, the simple and first two branched pectoral-fin rays are thin and shaped as those in females, the 3rd branched ray is somewhat thicker, still separated by membranes from the 2nd and 4th, while the next four branched rays are much thicker, with very narrow membranes between them ( Fig. 5). The branches are thickened too, fused along most of their length, separated only close to the tip where they have the same width as the branches of rays 1 and 2. These four rays appear as if covered by a thick skin. All branched rays have a band of small tubercles along their dorsal or antero-dorsal edge. The whole fin is stiff and curled upwards.

The holotype of N. maydelli is reportedly a male (Bănărescu & Nalbant, 1964). The figure of the holotype does not show any modification in the median pectoral-fin rays, but the authors mention "the rays of the pectoral, especially the median ones, are thickened and broad".

Šlechtová et al. (2008) reviewed the evolution of sexual dimorphism in the pectoral fin of Cobitidae in the context of a molecular phylogenetic study. Neoeucirrhichthys maydelli is included in their cladogram but, because of a missing line in the labelling of the lower part of their figure 7, it is not possible to see its position in their analysis of sexual dimorphism. The type of pectoral-fin sexual dimorphism reported here does nor appear in the caption and is unique within Cobitidae .

Remarks on Cobitis barbatuloides . Bleeker (1851: 435) described Cobitis barbatuloides on the basis of a single specimen 46 mm TL from Sambas, Kalimantan Barat. In the original description, he mentioned the presence of a bifid suborbital spine. Bleeker (1859: 304) modified the description of the species and said that the suborbital spine is missing; he later (1860: 82) explained that the holotype was in bad state and that he earlier must have confused the edge of the suborbital with a spine. The description is repeated and the holotype figured in the Atlas ( Bleeker, 1863a –64: 14, pl. 103 fig. 4). Since then, the species has not been reported or considered as valid. Bleeker (1863a –64: 14) commented that the holotype was very badly preserved. We examined it (RMNH 4960); the head is missing and the specimen has been desiccated: no information can be extracted from it. The figure in the Atlas ( Bleeker, 1863a –64) shows a loach with a conspicuous black spot in the upper half of the caudal-fin base. Among Southeast Asian species, this character is only observed in Lepidocephalichthys and Kottelatlimia . The figure also shows the dorsal-fin origin slightly behind the pelvic-fin origin. In Borneo, we have seen this condition only in a species of Lepidocephalichthys collected in Kalimantan Selatan and Kalimantan Tengah, which we presently identify as L. hasselti (see Kottelat & Lim, 1992). The figure of the holotype of C. barbatuloides , however, shows a more slender fish, with a very shallow head and a more or less uniform brown body. The black spot at caudal-fin base is much less conspicuous in L. hasselti (Valenciennes) . The area of Sambas has only been marginally collected since Bleeker's time (or at least no information is published) and the species is waiting to be re-discovered. In any case, the position of the dorsal fin (origin very slightly behind pelvic-fin origin) excludes the possibility that C. barbatuloides is identical with K. pristes , K. hipporhynchos (dorsal-fin origin in front of pelvic-fin origin), L. tomaculum Kottelat & Lim , L. sandakanensis (Inger & Chin) or L. lorentzi (Weber & de Beaufort) (dorsal-fin origin well behind pelvic-fin base). For the time being, we tentatively recognise C. barbatuloides as a species of Lepidocephalichthys .

Bleeker (1859) created the genus name Cobitichthys , with Cobitis barbatuloides as type species by monotypy. This genus name has been mentioned in the literature, but never as the name of a valid genus. Since the original description, it has been occasionally listed as a junior synonym of Misgurnus by Bleeker himself (1863a–64) and others (e.g., Berg, 1949: 899, Chen, 1981: 27). The figured holotype does not look like a Misgurnus (of which no species is known from Sundaland). As we consider that C. barbatuloides is likely a valid species of Lepidocephalichthys , this makes Cobitichthys a senior subjective synonym of Lepidocephalichthys (type species: Cobitis hasselti Valenciennes , in Cuvier & Valenciennes, 1846, by original designation).

Cobitichthys Bleeker, 1859 is here declared nomen oblitum and Lepidocephalichthys Bleeker, 1863 is here declared nomen protectum under Article 23.9.2 of the International Code of Zoological Nomenclature. To our knowledge, Cobitichthys has not been used as a valid name since 1860 [Art. 23.9.1.1] and Lepidocephalichthys has been used in at least 25 works, published by at least 10 authors, in the immediately preceeding 50 years and encompassing a span of not less than 10 years (art. 23.9.1.2]). This gives precedence to Lepidocephalichthys over Cobitichthys . A list of 27 publications satisfying these criteria includes: Arunkumar, 2000; Britz & Maclaine, 2007; Datta Munshi & Srivastava, 1988; Edds, 2007; Freyhof et al., 2000; Inger & Chin, 2002; Kottelat & Lim, 1992; Kottelat et al., 1993; Kottelat & Whitten, 1996; Kottelat, 1982, 1989, 1990, 1998, 2001; Nalbant, 1994; Ng, 2006; Ng & Edds, 2005; Pethiyagoda, 1991; Pillai & Yazdani, 1974; Rainboth, 2006; Roberts, 1989; Shrestha, 1981; Šlechtová et al., 2007, 2008; Vidthayanon, 2004; Vidthayanon et al., 2005; Vishwanath et al., 2007.