Patchwork Barbelgoby

Gobiopsis arenaria (Snyder)

Hetereleotris arenarius Snyder, 1908:100 [type-locality: Naha, Okinawa]; 1912:513, pl. 67: fig. 3.

Pipidonia arenarius Kamohara and Yamakawa, 1968:14, fig. 5 [Kikaijima, Japan].

DIAGNOSIS.—Sensory pores NA and PITO present, SOT almost always present, AT, PT, and POP absent; body slender, depth of caudal peduncle 24–30 percent of postanal length; scales cycloid, 33–36 in horizontal series; postmandibular barbel present, posterior gular barbels almost always present; jaw very short, its length about 10–13 percent of SL; dark wedge on head descends only to upper preopercle; light base of pectoral fin not divided by dark wedge; trunk with dark saddles joined at midbody, usually forming a continuous midlateral stripe with narrow extensions below stripe, head and trunk not mottled.

DESCRIPTION.—Dorsal fin rays VI–I, 9(1), VI–I,10 (17), VI–I,11(1); anal fin rays I,9 (19); pectoral rays 17(17), 18(22), 19(2); pelvic fin rays I,5(21); segmented caudal fin rays 17(20); branched caudal fin rays 15(14), 16(2), 17(1); lateral scale rows 33–36(16); transverse scale rows 13–17(14); predorsal scales 7–11(13).

Scales cycloid, primary radii in anterior field 13–14; scale eccentric; radii in posterior field short, numbering about 6–9; radii of anterior field converge broadly on a wide focal area.

Vertebrae 10+16(20), 10+17(1).

Head length 283 (260–299) 17; snout length 65 (59–73) 16; postorbital length 178 (164–187) 16; greatest diameter of orbit 41 (37–44) 16; bony interorbital width 39 (34–43) 12; pectoral fin length 249 (224–270) 15; pelvic fin length 188 (171–203) 14 caudal fin length 283 (255–308) 11; predorsal length 372 (357–391) 17; greatest depth of body 137 (121–159) 16; least depth of peduncle 102 (92–120) 23; postanal length 380 (357–399) 23; lower jaw length 119 (102–133) 12; pelvic fin insertion to anal fin origin 350 (314–380) 14. The latter measurement may be related to both sex and size; males (19.5–22.7 mm SL) have values ranging from 314 to 323 and females (22.5–30.1 mm SL) have values ranging from 332 to 380.

Body slender, snout from above pointy, head behind eyes narrow. A small species, largest male 25.2 mm SL, largest female 30.6 mm SL, a gravid female 25.2 mm SL. Trunk not deep, caudal peduncle narrow, least depth of peduncle about 24–30 percent of postanal length (Figure 5). Snout long, longer than width of fleshy interorbital; fleshy interorbital width somewhat greater than diameter of orbit; lower jaw short, about 10–13 percent of SL; origin of second dorsal fin slightly posterior to vertical at anal opening; depressed pectoral fin short, extending posteriorly to vertical from end of base of first dorsal fin, longer than deep, the margin rounded; pelvic fin short, shortest for the genus, about 54 percent length of distance from pelvic fin insertion to anal fin origin (Figure 3).

Number of teeth on outer row of upper jaw 14–17, on lower jaw 8–12.

The following cephalic sensory pores are absent: the POP, AT, and PT pores. The SOT pores are occasionally absent (Tables 1, 2).

The cutaneous papillae system is pattern 3. As in G. malekulae, there are 2 papillae in a vertical row at the midpreopercular margin, above and disjunct, but in line with the outer preoperculo-mandibular row and more posterior and disjunct from the upper preopercular row.

Barbels present in all defined positions except occasionally the posterior gular group is missing. The number of barbels, by particular groups, are: intermandibular, 1–3 (mean 2.30); posterior mandibular 2–4 (3.00); postmandibular 1 (1.00); posterior gular 0–2 (0.70); anterior cheek tuft 2–4 (3.26); anterior internasals 1–2 (1.45); posterior internasals 1–2 (1.35). Lower barbel on anterior cheek tuft is not elongate, but is about equal to or slightly longer than others on the tuft.

COLOR IN PRESERVATION.—Body strongly bicolored, the four prominent dark brown trunk saddles are in contrast with a predominately light colored body (Plates 7d, 8d).

Head from tip of snout to line between upper preopercular margins dark brown, more so behind the eyes, forming a broad, dark band that descends on the upper preopercle as a dark wedge; a light interopercular band between dark head band and first anteriormost dark trunk saddle, sometimes finely dusky; remainder of head whitish.

The 4 trunk saddles extend from the dorsal midline ventrally to about the midlateral body where they are together and form a lateral stripe, and are joined from the upper pectoral fin base to base of caudal fin; 5 narrow branches of the dark brown arcs between the saddles extend ventrally to about the ventrolateral part of the body; the first saddle is largest, squarish, and occurs in the predorsal area from about the upper interpectoral area posteriorly to before the origin of first dorsal fin; the second saddle, one-half width of first saddle, passes through the posterior part of first dorsal fin; the third saddle, about as wide as second, passes through the anterior portion of second dorsal fin; the fourth, smallest saddle, about one-half as wide as third saddle, passes through the base of last ray of second dorsal fin; the light dorsal areas between the dark saddles have some fine, brownish mottling; base of caudal fin with a well developed, dark vertical bar confluent with midlateral stripe, equal to or less than diameter of orbit, and as deep as base of caudal fin; remainder of body ventrolaterally and ventrally light to whitish.

Pectoral fin with dark brown sickle-shaped mark on upper part of the fin, touching the upper basal portion; sickle-shaped mark not dividing the light pectoral base into two parts by a dark anteriorly directed wedge, remainder of pectoral fin light or clear; pelvic and anal fins light to transparent; first dorsal fin with a small, dark basal spot between first two spines; another dark mark basally at fourth to sixth dorsal spines over second saddle; a dark basal mark on second dorsal fin between third to fifth rays over third saddle; a small, brownish basal spot on last ray of second dorsal fin over the fourth saddle; remainder of dorsal fins light to transparent; caudal fin primarily light with irregularly arranged, weak, brownish, elongate spots on rays. Definitive adult color pattern almost completely developed at 8 mm SL.

GEOGRAPHIC DISTRIBUTION.—Known from southern Japan, the Ryukyus, Taiwan, and Hong Kong (Figure 6). Koumans (1941:247) reported this species from the Andaman and Nicobar islands. We consider these to be erroneous records of G. arenaria; they probably represent specimens of G. quinquecincta. Our search of specimens did not reveal G. arenaria occurring west of Hong Kong. Koumans (1940:127, 130) placed G. quinquecincta Smith in the synonymy of G. arenaria which may account for these records. We were unable to obtain the specimens from these two islands studied by Koumans.

ECOLOGY.—The type-locality of Hetereleotris arenarius was characterized as “sandy pools” (Snyder, 1908:100). Collection sites listed in the material examined include tide pools, surge channels and rocky and coral reefs, but always with a bottom of rock or coral rubble. Gobiopsis arenaria is known from depths of 8.5 m. Most specimens were collected with ichthyocides.