Caragobius urolepis (Bleeker, 1852)

Edward O. Murdy & Koichi Shibukawa, 2003, A revision of the Indo-Pacific fish genus Caragobius (Gobiidae: Amblyopinae)., Zootaxa 301, pp. 1-12 : 5-9

Caragobius urolepis (Bleeker, 1852)

(Figs.1-2, Tables 1-2)

Amblyopus urolepis Bleeker, 1852 : 581 (type locality, Palembang, Sumatra, Indonesia) .

Caragobius typhlops Smith and Seale, 1906 : 81, figured (type locality, Rio Grande, Mindanao, Philippines) .

Trypauchenophrys anotus Franz, 1910 : 68, pl. 9, fig. 77 (type locality, Fukuura, Japan) .

Taenioides chilkensis Hora, 1923 : 757 (type locality, channel off Barhampur Island, Chilka Lake, Orissa, India) .

Brachyamblyopus olivaceus Herre, 1927 : 329 (type locality, Negros Oriental, Philippines) .

Caragobius geomys Fowler, 1935 : 161, figs. 129-130 (Bangkok, Thailand) .

Nudagobioides monserrati Roxas and Ablan, 1940 : 309, pl. 8 (Lingayan Gulf, Luzon, Philippines) .

Brachyamblyopus urolepis : Koumans, 1941: 299 ( new combination).

Material examined. (Total of 104 specimens, 15.1-71.5 mm SL). Thailand: Central Bangpakong River: USNM 265010, 1:62.6. Bangkok: ANSP 63078, holotype of Caragobius geomys Fowler , 56.0. Sumatra, Indonesia: Palembang, probably the Musi River: RMNH 4807, lectotype of Amblyopus urolepis Bleeker , 61.5; RMNH 34799, paralectotype of Amblyopus urolepis Bleeker , 58.9. Irian Jaya, Indonesia: Bintuni River: WAM P. 29953- 008, 2:19.0-23.5. Sabah, Malaysia: Tawau River: NSMT-P 49332, 3: 39.8-51.1. Mindanao, Philippines: near the mouth of the Rio Grande: USNM 55619, holotype of Caragobius typhlops Smith and Seale , 56.6; USNM 126384, paratype of Caragobius typhlops Smith and Seale , 50.8; USNM 151316, 1:56.0. Siquijor Island, Philippines: tidal inlet at Sabanj: USNM 243403, 45:32.9-71.5. Negros Oriental, Philippines: Canauay River, about 75 m upstream from mouth in tidal mangrove pool: USNM 243404, 32:23.2-58.7. Viti Levu, Fiji: mudflat on north side of Nangara Island: USNM 241794, 15:15.1-34.4.

Description. As for genus except as follows. Total elements in dorsal fin 36-43 (mean = 39.2); total elements in anal fin 31-36 (mean = 33.1), first element segmented, or segmented and branched; pectoral-fin rays 17-20 (mean = 18.4); anal-fin pterygiophores preceding the first hemal spine (AP) 4-7 (mean = 5.4); caudal vertebral count 18-22 (mean = 20.2); SL/TL 0.794-0.891 (mean = 0.824); pelvic-fin length (PEL)/HL 0.311-0.615 (mean = 0.494); predorsal length/SL 0.241-0.363 (mean = 0.287).

Scales only on posterior 25-30% of body, remainder of body and head lacking scales. 18-27 teeth on outer row of upper jaw; 12-28 teeth on outer row of lower jaw. Jaws terminating posteriorly at the vertical just anterior to posterior naris.

Anterior nares much closer together than posterior nares.

Color when fresh. No fresh specimens were available. Bleeker (1852) stated that his specimen had a greenish body with yellowish fins. Roxas and Ablan (1940) described Nudagobioides monserrati as yellowish in life. The photograph of a presumably freshly dead Brachyamblyopus (= Caragobius) urolepis in Kottelat et al. (1993) depicts a bluish gray head, a creamy white body, the pectoral-fin base blackish blue, and the fins translucent.

Color in alcohol. Head and body uniformly tannish brown with translucent fins. Some specimens with a brownish black area along posterior edge of pectoral-fin base; the color derives from a prominent blood vessel.

Preserved specimens were uniformly yellowish white according to Smith and Seale (1906), whereas Hora (1923) stated that the body was olivaceous gray with whitish fins. Herre (1927) said that preserved specimens of Caragobius typhlops had a bluish gray head and yellowish body, which became whitish on belly and underside of head, and yellowish gray posteriorly. Brachyamblyopus olivaceous had a dusky olive-brown body, slightly pale head, and yellowish fins (Herre, 1927). As described by Fowler (1935), Caragobius geomys was drab and pale with shades of gray on the head and translucent fins. Three dusky gray lines were also present on C. geomys : one extending from the terminus of the maxilla and one dorsal and ventral to the pectoral fin. However, none of these gray lines was evident when the holotype of C. geomys was examined.

Ecology. Akihito et al. (1984) reported that in Japan Brachyamblyopus anotus (= C. urolepis ) inhabits soft mud bottoms near river mouths. Chen and Fang (1999) stated that C. urolepis constructs burrows in the muddy substrate and feeds on zooplankton and crustaceans.

Distribution. East coast of India (Hora, 1923), Thailand (Fowler, 1935), Indonesia (Bleeker, 1852), the Philippines (Herre, 1927), northward to Taiwan (Chen and Fang, 1999), southern Japan (Akihito et al. 1984) and eastward to Fiji. Specimens have only been examined from Thailand, Indonesia, the Philippines, and Fiji. Because C. urolepis is found in burrows in silty mud habitats, it is difficult to collect, which may help explain its relative paucity in museum collections.

Remarks. The original description of C. typhlops Smith and Seale (1906) was based on five specimens (2-2.5 inches, or 50.8-63.5 mm); the type (USNM 55619) was indicated, but no other catalogue numbers were provided. In his discussion of C. typhlops , Herre (1927) stated that seven specimens (35-54 mm) comprised the original collection. The National Museum of Natural History houses the holotype and one paratype (USNM 126384). Böhlke (1953) reported on the holotype and another paratype of C. typhlops (CAS-SU 20008). Although stating that there were four paratypes, Eschmeyer (1998) provided catalogue numbers for only two, USNM 126384 and CAS-SU 20008. The disposition of the other paratypes remains a mystery. One of the specimens examined for this study (USNM 151316, 56.0 mm SL) came from the type locality and its other collection information is similar to that of the holotype; USNM 151316 may represent one of the missing paratypes.

A radiograph of the holotype (SMF 7432) of Trypauchenophrys anotus Franz (1910) was examined. Based on the data gathered from the radiograph (PF=3-1221, AP=6, total dorsal-fin elements 38, total anal-fin elements 33, vertebrae 10+21, no ribs on vertebra 3), we place this species in synonymy of C. urolepis . We question, however, the locality of the type (Fukuura, approximately 35º N); no other conspecifics have been collected or reported this far north in Japan. Akihito et al. (1984) reported Brachyamblyopus anotus (= C. urolepis ) only from two of the southernmost islands in Japan (Ishigakijima and Iriomotejima, both islands at approximately 24º N).

The syntypes of Taenioides chilkensis Hora (1923) were not examined; according to Eschmeyer (1998) they reside at the Zoological Society of India (ZSIF 10385/1). Synonymy was based on the original description and figure. The description of T. chilkensis clearly indicates distinctive features of Caragobius (i.e., continuous dorsal and anal fins, minute eyes, head deeper than body, short, muscular pectoral fins, and pelvic fins longer than pectoral fins), whereas the meristic values for the dorsal fins (37-38) and morphometric measures (as % of SL) for pelvic-fin length, pectoral-fin length, head length, and snout length are consistent with C. urolepis . The figure accompanying the description also served to confirm the synonymy and is reprinted here as Figure 1. Hora (1924) reconsidered the generic placement of Taenioides chilkensis and reassigned it to Trypauchenophyrs . Hora (1924) also provided a count of caudal vertebrae (20) for T. chilkensis that is consistent with Caragobius urolepis .

As type material for Brachyamblyopus olivaceus Herre (1927) and Nudagobioides monserrati Roxas and Ablan (1940) was destroyed during World War II, our synonymy is based on the original description and figure. For his new species, B. olivaceous , Herre (1927) described features of Caragobius (i.e., minute eyes, no chin barbels, broadly rounded pectoral fins, no sensory pores or ridges on head, and scales present only near caudal-fin base) and the total number of dorsal and anal fin elements (37-39 and 30-33, respectively) were consistent with C. urolepis . The accompanying figure also helped confirm the synonymy. Similarly, Roxas and Ablan (1940) provided descriptive features of Caragobius (i.e., scales only present on precaudal region, eyes very small and dorsally placed, pectoral fin short, broad, and round, dorsal and anal fins continuous with caudal fin) as well as the count of dorsal-fin elements (38) that support synonymization of Nudagobioides monserrati with C. urolepis . The figure of N. monserrati also supports this synonymy even though the precaudal region and caudal fin were imprecisely rendered.

Koumans (1953) provisionally synonymized Caragobius geomys Fowler (1935) with Brachyamblyopus urolepis [= C. urolepis ]. The holotype (ANSP 63078) of C. geomys was examined and a radiograph made. The examination of the holotype confirmed the presence of scales only on the posterior 25% of the body, which is diagnostic for C. urolepis . The data gleaned from the radiograph (PF=3-1221, AP=5, total dorsal-fin elements 39, total anal-fin elements 32, vertebrae 10+20, no ribs on vertebra 3), are consistent with C. urolepis . The morphometric measures are consistent as well. Therefore, we concur with Koumans (1953) and place this species in synonymy of C. urolepis .