Pterocryptis anomala (Herre, 1933)

Heok Hee Ng & Bosco P. - L. Chan, 2005, Revalidation and redescription of Pterocryptis anomala (Herre, 1933), a catfish (Teleostei: Siluridae) from southern China., Zootaxa 1060, pp. 51-64 : 52-59

Pterocryptis anomala (Herre, 1933)

(Fig. 1)

Herklotsella anomala Herre, 1933 : 179 (type locality: Hong Kong).

Parasilurus cochinchinensis (non Valenciennes) - Nichols, 1928: 5 (in part); Nichols, 1943: 35, fig. 5 (in part).

Silurus wynaadensis (non Day) - Tchang, 1936: 35, figs. 1-2; Tchang, 1960: 9, fig. 4.

Silurus sinensis (non La Cepède, non McClelland) Hora, 1937: 341 (type locality: Lunchow [=Longzhou], China) .

Silurus gilberti Hora, 1938 : 351 (replacement name for S. sinensis Hora, 1937 ); Haig, 1952: 100; Chen, 1977: 201, pl. 1 fig. 1; Yue, 1981: 177, fig. 146; Kobayakawa, 1989: 163, fig. 17; Dai, 1989: 271, fig. 206; Dai, 1999: 79, fig. 39.

Parasilurus anomalus - Man & Hodgkiss, 1981: 49.

Silurus cochinchinensis (non Valenciennes) - Haig, 1952: 99 (in part); Chen, 1977: 202, pl. 1 fig. 2; Yue, 1981: 178, fig. 147; Chen, 1984: 389, Fig. 263; Dai, 1989: 272, fig. 207; Liu, 1990: 288, fig. 174 (in part); Chong & Dudgeon, 1992: 92; Dai, 1999: 81, fig. 41 (in part).

Material. CAS 126769, holotype, 158.3 mm SL; Hong Kong market. CAS 114841 (2 paratypes), 105.7-126.9 mm SL; data as for holotype. AMNH 10404 (36), 26.5-123.5 mm SL; China: Fujian province, vicinity of Nanping, 26°52’N 118°7’E. AMNH 12142 (38), 47.6-171.1 mm SL ; AMNH 233617, 170.8 mm SL; China: Fujian province, Fuqing, Shizhu valley, 25°44’N 119°24’E. ASIZB 72972 (1), 119.7 mm SL; China: Guangxi province, Damingshan Nature Reserve, 23°27’N 108°26’E. ASIZB 72973 (1), 62.1 mm SL; China: Jiangxi province, Jiulianshan Nature Reserve, 570 m a.s.l., 24°35’N 114°28’E. ASIZB 72974 (1), 78.6 mm SL; China: Guangdong province, Chebaling Nature Reserve, 520 m a.s.l., 24°42’N 114°10’E, 17 Aug 2000. ASIZB 72975 (1), 104.4 mm SL; China: Guangxi province, Damingshan Nature Reserve, 23°27’N 108°26’E. CAS 130371 (1), 89.5 mm SL ; CAS 131659 (1), 132.0 mm SL; Hong Kong. HKU 283 (1), 96.7 mm SL; Hong Kong: New Territories, Lau Shui Heung. HKU 284 (1), 114.8 mm SL; Hong Kong: New Territories, Ho Chung. HKU 285287 (3), 99.6-160.6 mm SL; Hong Kong: Lantau Island, Tong Fuk. HKU 288 (1), 110.4 mm SL; Hong Kong: Lantau Island, Sha Lo Wan. HKU 289 (1), 53.7 mm SL; Hong Kong: New Territories, Lam Tsuen. KFBG 281 (1), 127.5 mm SL; China: Guangdong province, Nanling Nature Reserve, Longtanjiao station, 350 m a.s.l., 25°0' ’N 112°0’E. KFBG 287 (1), 96.2 mm SL; China: Guangdong province, Guanyinshan Nature Reserve, 300 m a.s.l., 23°58’N 113°30’E. ZRC 45958 (1), 121.4 mm SL; Hong Kong: New Territories, Tai Shui Hang. USNM 293933 (1), 68.5 mm SL; China: Guizhou province, Beipanjiang.

Diagnosis. Pterocryptis anomala can be distinguished from P. cochinchinensis , the only other congener found in southern China, in having a small conical papilla in both sexes (vs. long conical papilla in male P. cochinchinensis and large leaf-shaped papilla in female P. cochinchinensis ; Fig. 2), and a deeper caudal peduncle (7.2-9.7% SL vs. 6.2- 7.6). The key characters distinguishing P. anomala from other congeners are presented in Table 1.

Description. Biometric data is given in Table 2. Body laterally compressed. Head somewhat depressed. Dorsal profile straight, descending gently from dorsal-fin origin to snout tip. Anterior profile of snout rounded. Anterior pair of nostrils tubular and anteromedial to maxillary barbel base. Posterior pair of nostrils bordered by fleshy dorsal and ventral membranes and situated posteromedial to maxillary barbel base. Eyes small, subcutaneous; located in anterior half of head; visible dorsally, but not ventrally.

Mouth subterminal; gape horizontal or very slightly oblique. Well-developed rictal fold present, consisting of large and fleshy upper lobe joined at corner of mouth with lower lobe; lower lobe subtended by short submandibular groove.

Teeth villiform. Dentary teeth in slightly curved, elongate bands narrowing posteriorly, reaching from symphysis almost to mouth corners; premaxillary teeth in broader, slightly curved rectangular bands; vomerine teeth in a single crescent-shaped band.

Maxillary barbels slightly flattened, reaching to anterior third of anal fin. One pair of mandibular barbels present; located slightly anterolateral to gular fold; barbels flattened for most of length, reaching to middle of pectoral-fin base.

Gill membranes separate and overlapping, free from isthmus. Branchiostegal rays 9 (3), 10 (35), 11 (18), 12 (4) or 14 (1). Gill rakers short, anteriormost rakers on lower first arch small and widely spaced; 2+4 (6), 1+6 (3), 2+5 (9) 2+6 (1), 3+5 (8), 4+5 (1) or 3+7 (1).

Distal margin of dorsal fin pointed, with i,2,i (50) or i,3,i (11) rays; segments of first ray not co-ossified to form spine. Distal margin of pectoral fin broadly convex, with 9 (1), 10 (5), 11 (46) or 12 (9) rays. Segments of the proximal two-thirds of first pectoral-fin element co-ossified, forming spine. Pectoral spine and articulated segments sexually dimorphic in mature individuals. Spine in males with broad and somewhat flattened dorsoventrally, with 5-9 serrations on posterior edge, increasing in size distally; proximal articulated segments with 0-6 serrations on posterior edge. Spine in females or juveniles slender, with 0-7 small serrations on posterior edge, and 0-3 serrations on posterior edges of proximal articulated segments. Distal margin of pelvic fin convex, with i,6,i (44) or i,7,i (17) rays. Distal margin of anal fin straight, with 59 (7), 60 (4), 61 (10), 62 (6), 63 (9) 64 (4), 65 (3), 66 (8), 67 (5), 68 (3) or 69 (2) rays; joined to caudal fin for length of last anal-fin ray. Integument over anal fin thickened proximally for slightly more than half of ray lengths; fin-ray erector muscles extending along anterior edges of anal-fin rays, ventralmost extent of muscles that of thickened integument. Caudal fin emarginate; principal rays i,6,6,i (34), i,6,7,i (25), i,7,6,i (1) or i,7,7,i (1).

Urogenital papillae of both sexes located immediately posterior to anus. Males (9 specimens examined, 78.2-171.1 mm SL) with a small conical papilla; females (16 specimens examined, 62.1-144.8 mm SL) with a similar shaped, but smaller, slightly broader papilla.

Vertebrae 14+39=53 (1), 13+41=54 (2), 14+40=54 (5), 15+39=54 (1), 13+42=55 (1), 14+41=55 (7), 15+40=55 (9), 14+42=56 (4), 15+41=56 (19), 16+40=56 (3), 14+43=57 (2), 15+42=57 (5) or 16+41=57 (2).

Coloration. In 70% ethanol: flanks and thickened integument over anal fin pale brown, with indistinct randomly distributed irregular dark patches. Dorsal surface and sides of head uniformly brown. Ventral surfaces of head, breast and belly yellow with scattered melanophores; melanophores less dense ventral to level of eye. Maxillary and mandibular barbels brown, fading to yellow distally. Anal fin with hyaline ventral margin. Caudal, pectoral and pelvic fins hyaline, with occasional small dark-brown spots.

Colour in life similar, except for more variation (yellow, brown or greenish) and lack of dark patches on dorsal surface and sides of head (Fig. 3).

Distribution. Minjiang and Zhujiang (Pearl River) drainages southwards to the streams draining the territory of Hong Kong Special Administrative Region, China (Fig. 4). In Hong Kong, the species occurs in the New Territories (adjoining the coast of southeastern China) and Lantau Island. This species is not known from Hong Kong Island.

Habitat and ecology. Pterocryptis anomala is found in habitats from sea level to at least 760 m a.s.l. (M. Lau, pers. comm. to BPLC). It prefers boulder-strewn, fast-flowing streams with step-pool formation. The fish are largely nocturnal and hides amongst rocks and submerged plant roots during the day, but can be seen during overcast days or in shaded stream pools. When active, P. anomala hovers near the streambed searching for small invertebrates. Stream water in Hong Kong is typically soft, slightly acidic, with a conductivity of less than 50µs/cm, and dissolved oxygen level between 0.4-1.0 mg/L (BPLC, unpubl. data). Fish species typically found syntopically with P. anomala include Parazacco spilurus spilurus , Psuedograstromyzon myersi , Liniparhomaloptera disparis disparis , Schistura fasciolata , Oreonectes platycephalus , and Rhinogobius duospilus .

Discussion

In the original description of P. anomala , the lack of pelvic fins in the holotype was the basis of its placement in a separate genus ( Herklotsella ). Since then, Bornbusch (1991) found that the lack of pelvic fins is a teratology that commonly occurs in the Siluridae. In previous studies (see below), the validity of P. anomala has not been discussed in detail. Kobayakawa (1989) did not mention this species; Bornbusch (1991) noted this omission but did not further discuss the status of P. anomala . Most recently, Ng & Freyhof (2001) tentatively considered P. anomala a junior synonym of P. cochinchinensis following Haig (1952) and Chen (1977). Our examination of material from Hong Kong and southern China shows that P. anomala is not conspecific with P. cochinchinensis and is a distinct species.

Our study shows that Pterocryptis cochinchinensis is found only in Hainan Island, southern China and central Vietnam (we could not find any clear differences between the populations in these places). Pterocryptis cochinchinensis is a distinctive species easily diagnosed by the large genital papilla of both sexes compared to the size of the genital papilla in congeners. Although we have not examined a significant amount of material from the Red River drainage, we suggest that previous records of P. cochinchinensis from the Red River drainage to refer to P. verecunda instead of P. anomala (based on the known distributions of the species). Furthermore, it is highly likely that material identified as P. gilberti from the Red River drainage in northern Vietnam by Mai (1978) refers to P. cucphuongensis , as evidenced by the relatively low anal-fin ray count reported (53-59 vs. 51-54 previously recorded for P. cucphuongensis ).

The diagnostic characters (number of mandibular barbels, shapes of genital papillae and degree of fusion of anal and caudal fins) found useful in distinguishing Pterocryptis have been discussed by Ng & Freyhof (2001) in their review of Vietnamese Pterocryptis . Our study of the Chinese Pterocryptis casts doubt on the utility of the number of mandibular barbels as a diagnostic character, however. It has been recognized that the outer mandibular barbels in some silurid genera (including Pterocryptis ) regress ontogenetically (Atoda 1935; Majumdar, 1951; Parameswaran et al., 1971; Xie, 1989; Bornbusch, 1995), but Ng & Freyhof (2001) considered the number of mandibular barbels useful as a diagnostic character when comparing specimens of at least 75 mm SL. Our examination of P. cochinchinensis reveals that there are individuals larger than 75 mm SL with two pairs of mandibular barbels ( KFBG 250, KFBG 251 and KFBG 278). No other differences could be found between the individuals with two pairs of mandibular barbels and others from Hainan Island with one pair of mandibular barbels, so we consider all of this material to be conspecific. Although we have not been able to examine Pterocryptis larger than 75 mm SL from mainland southern China with two pairs of mandibular barbels [the only specimen available to us is one of 68.5 mm SL ( USNM 293933)], the single specimen with two pairs of mandibular barbels is not otherwise distinguishable from congeners collected from southeastern China (with one pair of mandibular barbels). Pterocryptis with two pairs of mandibular barbels have long thought to be a distinct species, P. gilberti (e.g. Dai, 1999). As noted above, we were otherwise unable to distinguish between material identified as P. anomala and P. gilberti (save for number of mandibular barbels). We also note here that Chen (1977) mentioned that material with two pairs of mandibular barbels has a shorter head (14.6-16.1% SL vs. 16.8-17.6), but because we are unable to verify this, we tentatively concur with Ni & Wu (1986) in placing P. gilberti in synonymy with P. anomala .

Although we have established that variation in the number of mandibular barbels in individuals larger than 75 mm SL exists in P. cochinchinensis , it is difficult to extrapolate this to other species. This is primarily because all other congeners diagnosed in having two pairs of mandibular barbels (i.e. P. bokorensis , P. buccata , P. burmanensis , P. cucphuongensis , P. indicus and P. wynaadensis ) are known from very little material (not more than five specimens in each case). These six species have been traditionally diagnosed by the number of mandibular barbels, but in the light of these difficulties, we tentatively regard the six species mentioned above as valid, but have refrained from using the number of mandibular barbels to diagnose them.