Siphamia fistulosa (Weber)

Gon, Ofer & Allen, Gerald R., 2012, 3294, Zootaxa 3294, pp. 1-84 : 37-39

Siphamia fistulosa (Weber)

Figures 14e–f, 18

Foa fistulosa Weber, 1909: 162 (type locality, Bima Bay , Sumbawa, Indonesia; syntypes, ZMA, apparently lost).

Diagnosis: Dorsal rays VII+I,9; anal rays II,8; pectoral rays 12 (rarely 11 or 13); tubed lateral-line scales 8–13; median predorsal scales 4 or 5; total gill rakers 3–4 + 9–11; developed gill rakers 1 + 7–9; gill rakers on ceratobranchial 6–7. Body relatively short and deep, depth 2.2–2.5 in SL and body width 2.1–2.4 in the depth; eye diameter 2.5–2.8 in head length; first dorsal spine 2.9–3.4 in second spine; second dorsal spine 3.9–5.4, spine of second dorsal fin 3.8–4.5, and second anal spine 4.5–5.4, all in head length; pectoral-fin length 4.3–4.55 and pelvic-fin length 3.85–4.9 in SL; caudal-peduncle length 1.5–2.3 in distance between pelvic spine insertion and anal-fin origin. Preopercular edge with 10–22 (usually 12–16) serrations around angle; preopercular ridge smooth. Scales spinoid. Palatine teeth present or absent. Tip of light organ on each side of tongue bound by membrane.

Colour when fresh (from colour slide by J.E. Randall): body cream peppered with small dark dots; top of head, snout, jaws and throat with larger, dense orange dots; iris with reddish-orange ring around pupil; scales with reddish orange edges gradually becoming thinner posteriorly and faint on caudal peduncle; dark brown dots along posterior part of upper and lower jaws, and along branchiostegal rays; fins pale; light organ with dark brown dots.

Colour in alcohol: pale brown with minute dark brown dots mostly on anterior part of body and head; dots usually denser on shoulder and below first dorsal-fin base, becoming more spaced ventrally and posteriorly; relatively wide dark brown cheek stripe from ventral edge of eye to angle of preopercular ridge, sometimes continuing to pectoral-fin base; iris with dark brown ring around pupil; branchiostegal rays with dark brown dots; similar dots along ventral edge of preopercular ridge; fins pale or with dark dots scattered on their proximal part; peritoneum with dark dots of various sizes; stomach with scattered smaller dark dots.

Smallest and largest specimen examined, 14.0 mm and 22.9 mm, respectively, both in UNSM 261578, from Pulau Seribu, Indonesia.

Remarks: See Tables 1–3 for frequency distributions of pectoral-fin rays, lateral-line scales and gill rakers. The median predorsal scales count was based on scale pockets. Palatine teeth, when present, were very small and in a single series usually of few teeth anteriorly, rarely extending beyond the middle of the bone. The light organ of this species is relatively short. It ended at about the middle of the caudal peduncle in the largest specimen (27.4 mm).

This species is a member of the S. tubulata species group. It is most similar to S. brevilux , S. cyanophthalma and S. senoui with which it shares a pectoral-fin ray count of, usually, 12 and a general colour pattern. Siphamia brevilux has fewer tubed lateral-line scales ( Table 2) and a shorter light organ that is 9.7–20.75 in the caudal peduncle length ( Fig. 3c), versus 1.9–17.3 in S. fistulosa . It also has a narrower interorbital space (5.1–5.8 versus 4.1–5.3, respectively). In life S. cyanophthalma is easily distinguished by the characteristic blue horizontal lines across its eye. The latter species and S. senoui are modally different from S. fistulosa in their tubed lateral-line scale count ( Table 2). The higher number of tubed lateral-line scales ( Table 2), the modally lower count of developed gill rakers ( Table 3) and the colour pattern of dark dots all over the body, usually with dark irregular markings, separate S. tubulata from this species. Similarly, the mottled colour pattern, lower count of pectoral-fin rays ( Table 1), more slender body (depth 2.6–3.3 in SL), smaller eye (diameter 2.9–3.7 in head length), and shorter pectoral and pelvic fins (5.1–6.1 and 4.5–5.3, respectively, in SL) separate S. corallicola and S. elongata from S. fistulosa . See Tables 1–3 and the Remarks section in the respective species accounts for differences from the three Australian endemics, S. cephalotes , S. cuneiceps and S. roseigaster .

The type specimens (nine according to Weber 1913), are apparently lost ( Nijssen et al. 1982). Weber (1909) described this species as having 13 pectoral-fin rays, 9 developed gill rakers and 11–13 tubed lateral-line scales. Although there is a slight discrepancy in pectoral rays (usually 12), the specimens we examined otherwise agree closely with Weber’s original description. The only other species with a lateral line count that falls in this range is S. corallicola which usually has 11 pectoral rays ( Table 2). As evident from his description of Apogon tubulatus (see Remarks for S. tubulata below), it appears that Weber sometimes used data of only one of several specimens for a description. In this case he may have chosen a fish with the unusual count of 13 pectoral-fin rays.

At present S. fistulosa is known from specimens collected in Pulau Seribu, Sumbawa (the type locality) and Komodo Island in Indonesia, from depths of 0– 30 m. An underwater photograph ( Fig. 14f) of this species, taken by the second author in Brunei, was identified as this species and is included in the distribution map ( Fig. 7). This species was observed hiding in Seriotopora hystrix branching corals (M. Erdmann, Conservation International, pers. comm.)ni

Material examined: INDONESIA: Jakarta, Pulau Seribu, USNM 261577, 4: 15.4–19.8 mm; USNM 261578, 25: 14.0– 22.9 mm; USNM 339771, 20.7 mm. Komodo Island, BPBM 32378, 27.4 mm.