Balitoropsis zollingeri ( Bleeker 1853 )

Randall, Zachary S. & Riggs, Patrick A., 2015, Revision of the hillstream lizard loaches, genus Balitoropsis (Cypriniformes: Balitoridae), Zootaxa 3962 (1), pp. 206-225 : 212-219

Balitoropsis zollingeri ( Bleeker 1853)

Black Lizard Loach ( Figures 2 , 3 , 4 , 5 , 6 A, 7)

Homaloptera javanica van Hasselt 1823: 133 (nomen nudum, Kottelat, 1987)

Homaloptera Zollingeri Bleeker 1853: 159 (type locality: Indonesia: Java: Batavia [Jakarta] and Bandong [Bandung]); syntypes: lost, Bleeker, 1860: 89

Homaloptera javanica Bleeker 1860: 89 (unnecessary replacement name for Homaloptera zollingeri Bleeker, 1853 )

Homaloptera maxinae Fowler 1937: 152 , figs. 52, 53 (type locality: Tachin [Tha Chin, Samut Sakhon], Siam [ Thailand]); holotype: ANSP 68004

Balitoropsis bartschi Smith 1945: 279 , fig. 56 (type locality: Thailand: Trang Province: waterfall stream on Kao Chong); holotype: USNM 107963

Homaloptera nigra Alfred 1969: 217 , pl. 1 figs. 1–2 (type locality: Malaysia: Pahang: King George V National Park [now Taman Negara], Chegar Sireh, Tahan River); holotype: ZRC 2009

Balitoropsis zollingeri . — Kottelat 2012: 47

Remarks. The three specimens examined in the original description of Homaloptera zollingeri Bleeker 1853 were lost after several moves of Bleeker’s collection or from theft ( Bleeker 1860). Gunther (1868) assumed that one of the three specimens sent to him by Bleeker was a type ( Norman and Whitehead 1984:305), and recognized it as the holotype (catalog number not listed, but it would correspond to BMNH 1866.5.2.53 [1]). This specimen is from Lahat, Sumatra, and not from the type localities of B. zollingeri (Jakarta and Bundung, Java). Specimens of B. zollingeri from the type localities are unknown to us.

Bleeker (1860) synonymized H. zollingeri Bleeker 1853 with H. javanica van Hasselt 1823 after examining specimens of H. zollingeri from Lahat, Sumatra, and noting its resemblance to the original unpublished drawings of H. javanica . However, the name H. javanica lacked a description or figure and is unavailable ( Kottelat 1987). The first available name for this species is H. zollingeri (Art. 12.1, ICZN 1999).

Homaloptera maxinae Fowler 1937 was described from Tachin (Samut Sakhon), Thailand. After examining its holotype (ANSP 68004), Smith (1945) synonymized H. maxinae with H. zollingeri commenting that putative differences might be due only to age. The only character differentiating the holotype of H. maxinae (ANSP 68004) ( Fig. 2 and Table 2) from other B. zollingeri is head width (68.8% vs. 69.4–87.4% HL), which may be unreliable due to the poor condition of the holotype. See Smith (1945) for comments on miscounts in Fowler’s (1937) original description of H. maxinae . Silas (1953) tentatively followed Smith’s synonymization of H. maxinae, Rainboth (1996) treated H. maxinae as valid, and Kottelat (2012, 2013) recognized it as a questionable junior synonym of Homalopteroides smithi ( Hora 1932) .

Balitoropsis bartschi Smith 1945 was described from Kao Chong River, Trang Province, Thailand, as the type of the genus. Following Kottelat and Chu (1988) and Randall and Page (2015), Balitoropsis bartschi is a junior synonym of B. zollingeri .

Homaloptera nigra Alfred 1969 was established based on populations in the Malay Peninsula and distinguished from H. zollingeri by color and squamation on the ventral surface of the body. Roberts (1989) synonymized H. nigra with H. zollingeri after finding only slight differences between specimens of H. zollingeri from the Kapuas drainage of Borneo and type material of H. nigra . Kottelat (2001, 2012, 2013) followed the classification of Roberts (1989).

Comparison of the type series of H. nigra ( Fig. 3 and Table 2) with specimens of B. zollingeri shows no distinction in morphometrics or meristic counts. Pigmentation varies among individuals throughout the range of B. zollingeri , with some individuals being much darker than others, likely due to variation in habitat substrate. Squamation on the ventral surface varies intraspecifically ( Fig. 4 ) but shows no geographic pattern. Two of the four individuals in Figure 4 (B & C) differ in squamation but clearly are indicated as conspecific in the phylogenetic analysis ( Fig. 1 ).

Diagnosis. Member of Balitoropsis as defined by Randall and Page (2015). Balitoropsis zollingeri is distinguished from B. ophiolepis (Table 3) by mostly black caudal-fin with 1–3 black bands on distal extremity of white upper lobe vs. hyaline with multiple black bands; caudal-peduncle depth 8.0–9.3% vs. 4.0–5.1% SL; body depth 13.6–17.6% vs. 9.2–11.9% SL; 42–46 vs. 48–55 total lateral-line scales; and 17–20 vs. 13–14 circumpeduncular scales.

TABLE 3. Characters distinguishing species of Balitoropsis . Number of specimens examined in parentheses. Description. Dorsal, lateral, and ventral views of B. zollingeri are shown in Figure 5 . Measurements and meristic counts are given in Table 2. Body arched predorsally and flattened ventrally. Head with two rows of prominent tubercles longitudinally between nares. Eyes dorsolateral, shorter than interorbital width. Rostral cap large. Dorsal-fin origin anterior to or at pelvic-fin origin. Pectoral fin reaching about midway between pectoral-fin insertion and pelvic-fin origin. Pelvic fin reaching far past anus. Anus closer to pelvic-fin base than to anal-fin origin. Anal fin not reaching caudal-fin base. Axillary pelvic lobe absent. Caudal fin forked with rounded lobes; lower lobe longer.

Dorsum with large keeled scales; scales on ventral surface without keels, deeply embedded between pectoral and pelvic fins. Total lateral-line scales 42–46, predorsal scales 13–15, circumpeduncular scales 17–20. Scales above and below lateral line 5–7/5–6, respectively. Scales below lateral line to pelvic-fin origin 5–6. Modal fin-ray counts (variation given in Table 2): dorsal iii, 8½; anal ii, 5½; pectoral iv, 10, i; pelvic ii, 8; total caudal 17.

Mouth ( Fig. 6 A) inferior; lips with tiny unculi, continuous around corners of mouth. Distal-lateral extension of lower lip uncommon. Fleshy pad present between lateral halves of lower lip. Rostral and post-labial grooves present. Two pairs of rostral barbels, one pair of maxillary barbels. Barbels with tiny unculi, rostral barbels in close proximity to each other. Medial-rostral barbels separated at base. Lateral-rostral barbel longer than medial-rostral barbel, reaching to maxillary barbel. Maxillary barbel reaches horizontally to vertical at anterior orbital rim. Under surface of head covered in small tubercles; branchiostegal membrane united to isthmus with small central furrow.

Color in 70% ethanol ( Fig. 5 ): Dorsally light-dark brown with dark brown mottling. Some specimens dark overall with dorsal saddles hard to differentiate. Six brown-black dorsal saddles usually present. 1st saddle between supraoccipital and 2nd saddle; 2nd saddle from anterior to dorsal-fin to just behind origin of fin; 3rd saddle spans most of dorsal-fin length; 4th saddle between distal extremity of dorsal-fin to just past anal-fin origin; 5th saddle spans most of anal-fin length; 6th saddle at caudal-fin base. In some individuals, 5 (5th and 6th saddle fused) or 7 (extra saddle between 2nd and 3rd saddles) saddles present. Brown-black triangular blotch between posterior orbital margins and supraoccipital.

Venter cream; heavily stippled posterior to anal-fin origin, less so between anal and pectoral fins, stippling becoming patchy near head. Undersurface of head heavily stippled dark brown. Barbels stippled brown with hyaline tips. Lips and fleshy pad lightly stippled brown.

All fins dark brown-black; sometimes 2–3 black bands on dorsal fin. Caudal fin mostly black; 1–3 small black bands on clear portion of upper lobe, white tips on upper and lower lobes.

Color in Life. Live large and small individuals shown in Figure 7 . Both have similar color pattern with exception of orange infraorbital blotch in smaller individual. Head, body, and fins stippled black. Orange mottling on head, highlighting dorsal saddles, and on hyaline portions of fins. Large orange-red patch between pectoral fins on larger individual.

Distribution and Ecological Notes. No recent collections are known from the type localities of Jakarta and Bandung, Java, and the species has likely been extirpated from these highly developed areas. The species is known to occur in Sumatra: Lampung (Tulangbawang basin) and Sumatera Selatan (Musi basin); Borneo: Kalimantan Barat (Kapuas basin) and Kalimantan Selatan (Barito basin); peninsular Malaysia: Pahang (type locality of Homaloptera nigra ) (Pahang basin), Negri Sembilan (Muar basin), Kelantan (Kelantan basin), Terengganu (Setiu basin), and Johore (Endau basin); Thailand: Samut Sakhon (type locality of Homaloptera maxinae ) (Chao Phraya basin), Nakhon Si Thammarat (Ta Pi and Mai Siap basins), and Trang (type locality of Balitoropsis bartschi ) (Trang basin); Cambodia: Stung Treng (Mekong basin) ( Fig. 8 ). The species was reported from the Mekong River, downriver of Khone Falls in Laos ( Kottelat 2001).

Balitoropsis zollingeri has been collected from fast-flowing waters with rocky substrates and is reported to feed on insect larvae ( Rainboth 1996). In the Kapuas basin, B. zollingeri was collected syntopically with B. ophiolepis (field number Kapuas 1976-27, Roberts 1989).

Material examined.— Balitoropsis zollingeri : Sumatra: BMNH 1866.5.2.53 (Bleeker specimen) (1); UF 161715 (3), 166094 (2), 166095 (1), 166102 (1), 166105 (1). Borneo: CAS 49331 (1); USNM 230253 (2); USNM 393008 (1). Thailand: ANSP 68004 (Holotype of Homaloptera maxinae ); UF 183727 (1), 183812 (1), 235545 (2); USNM 107963 (Holotype of Balitoropsis bartschi ) (Photo only). Malaysia: CAS-SU 66420 (2), 66424 (Paratypes of Homaloptera nigra ) (2); USNM 288456 (1); UF 235547 (9), 235421 (2), 235420 (1); ZRC 2009 (Holotype of Homaloptera nigra ).

Figures

FIGURE 1. Balitorid phylogeny based on Bayesian analysis of CO 1. Support values are indicated at the branch lengths (pp / bs). Posterior probability values ≥ 0.95 and bootstrap support ≥ 90 are represented by an asterisk (*). Support values ≤ 50 are represented by a hyphen (-). M) peninsular Malaysia; S) Sumatra; T) Thailand.

FIGURE 2. Dorsal, lateral, and ventral views of holotype of Homaloptera maxinae, ANSP 68004, 34.3 mm SL; Tachin (Samut Sakhon), Thailand.

FIGURE 3. Dorsal, lateral, and ventral views of holotype of Homaloptera nigra, ZRC 2009, 50.1 mm SL; Pahang, Malaysia.

FIGURE 4. Ventral squamation pattern of preserved Balitoropsis zollingeri. (A) CAS-SU 66424 (paratype of Homaloptera nigra), 57.0 mm SL; Pahang, Malaysia. (B) UF 235547, 61.7 mm SL; Kelantan, Malaysia. (C) UF 183727, 64.4 mm SL; Nakhon Si Thammarat, Thailand. (D) CAS-SU 49331, 67.7 mm SL; Kalimantan Barat, Borneo. Squamation pattern shaded. Anterior at top of figure.

FIGURE 5. Balitoropsis zollingeri. (A) Dorsal, lateral, and ventral views of UF 166094, 52.1 mm SL; Sumatera Selatan, Sumatra; scale bar 30 mm. (B) UF 235545, 32.1 mm SL; Nakhon Si Thammarat, Thailand. (C) USNM 288456, 27.9 mm SL; Pahang, Malaysia. Scale bar for B and C 10 mm.

FIGURE 6. Oral morphology of (A) Balitoropsis zollingeri, UF 166094, 52.1 mm SL; Sumatera Selatan, Sumatra, (B) B. ophiolepis, UF 166109, 101.2 mm SL; Lampung, Sumatra. Scale bar 3 mm.

FIGURE 7. Lateral views of living Balitoropsis zollingeri. (A) UF 235547, 61.7 mm SL; Kelantan, Malaysia. (B) UF 235545, 27.3 mm SL; Nakhon Si Thammarat, Thailand. Scale bar 5 mm.

FIGURE 8. Distribution of Balitoropsis. Locality in Cambodia from Rainboth, et al. (2012).