Siphamia corallicola Allen

Gon, Ofer & Allen, Gerald R., 2012, 3294, Zootaxa 3294, pp. 1-84 : 28-30

Siphamia corallicola Allen

Figures 13, 14a

Siphamia corallicola Allen, 1993: 12 , figs. 4–6 (type locality, Tab Island , Madang, PNG; holotype, WAM P.30337-009).

Diagnosis: Dorsal rays VII+I,9; anal rays II,8; pectoral rays 11–12, unbranched and compressed distally; tubed lateral-line scales 6–13; median predorsal scales about 5–6 (2 specimens); total gill rakers 2–4 + 9–10; developed gill rakers 1 + 7–8; gill rakers on ceratobranchial 6 (rarely 7). Body ovate, its depth 2.6–3.1 in SL, and body width 2.0– 2.7 in the depth; eye diameter 2.9–3.6 in head length; first dorsal spine 3.3–4.3 in second spine; second dorsal spine 3.0–4.8, spine of second dorsal fin 3.0–3.9, and second anal spine 3.0–4.3, all in head length; pectoral-fin length 5.1–6.1 and pelvic-fin length 5.0– 5.3 in SL; caudal-peduncle length 1.1–1.4 in distance between pelvic spine insertion and anal-fin origin. Preopercular ridge smooth; preopercular edge with 0–12 (usually 6–10) fine serrations. Vomer with narrow band of small teeth forming v-shape; palatines with narrow band of small teeth. Scales weakly spinoid, but cycloid on anterior part of body below lateral line and area covered by pectoral fin. Tip of light organ on each side of tongue bound by membrane.

Colour in life (from underwater photo taken by G.R. Allen): head and body covered with large red-brown blotches with narrow silvery interspaces, sometimes forming 4–5 widely spaced pale bars on side; diffuse, vertically ovate, brown spot covering base of caudal fin; fins translucent.

Colour in alcohol: generally pale tan with variable pattern of irregular brown blotches on head and body; a faint backward slanting brown band on cheek below rear corner of eye; distinct vertically ovate, brown spot covering base of caudal fin; a faint narrow brown bar across pelvic fin bases; greyish luminescent gland along belly, extending on to lowermost part of caudal peduncle, the gland containing numerous dark brown spots (contracted melanophores), its dorsal edge darkly pigmented; fins uniformly pale tan or whitish; palate and dorsal surface of tongue with scattered dark brown spots (contracted melanophores); peritoneum with large, conspicuous dark brown spots; stomach and intestine with fewer, smaller dark brown spots.

Smallest specimen examined, 14.3 mm, and largest specimen 30.5 mm, both from Madang, PNG.

Remarks: See Tables 1–3 for frequency distributions of pectoral rays, lateral-line scales and gill rakers. One specimen 18.4 mm (CAS 63655) had no palatine teeth. The dark brown spot across the caudal-fin base becomes indistinct when its melanophores contract into small dark dots. However, these dots are larger and usually darker than most other dark dots scattered on the side of the body.

Siphamia corallicola is a member of the S. tubulata species group and appears to be closely related to S. elongata from the Philippines. Both species have similar morphometrics and counts for fin rays and gill rakers ( Tables 1, 3). However, they differ in the number of tubed lateral-line scales and the number of serrations on the preopercular edge, with S. elongata having 17–23 and 11–27, respectively. In addition, S. elongata seems to have a longer third dorsal spine (2.3–2.7 in head length versus 2.9–3.1 in head length in S. corallicola ). Siphamia elongata also appears to attain a slightly larger size (to 36 mm SL). See Tables 1–3 for differences between S. corallicola and the remaining species of the S. tubulata group in the numbers of pectoral-fin rays, tubed lateral-line scales and gill rakers. In addition, S. cephalotes and S. cuneiceps are distinguished from S. corallicola in having a more elongate body (depth 3.2–4.8 in SL) and a longer first dorsal spine (1.1–1.3 in second spine), while S. roseigaster differs in having 10–11 soft rays in the dorsal and anal fins, as well as a free-ending light organ in the mouth.

Siphamia corallicola is a relatively small species. The smallest male specimen with an enlarged buccal cavity (evidence of oral egg incubation) was 21.4 mm SL. A buccal egg mass was collected from a live male, 25.0 mm SL, at Madang. It contained 162 eggs, each with a diameter of 0.95–1.0 mm. Freshly hatched larvae were about 2.8 mm TL. The smallest mature female (visual examination) was 23.3 mm SL ( BPBM 37647 ) .

This species was originally collected in the vicinity of Madang, Papua New Guinea and in two locations at Sabah, Malaysia (northern Borneo) ( Allen 1993). More recently, Allen and Adrim (2003) reported it from Bali, Indonesia, based on field observations. In addition, we found museum specimens that were collected at Siberut Island (off western Sumatra) and Sulawesi, Indonesia; Cebu Island, Philippines; and the Timor Sea ( Fig. 7). This species appears to be relatively widespread in the Indo-Malayan region, but is difficult to detect due to its small size and cryptic behaviour. The habitat consists of sheltered waters of lagoons and coastal inlets at depths between about 6– 22 m. At Madang and Sabah it was generally seen in groups of approximately 30–40 individuals, often hovering beside or among growths of the pocilloporid coral Seriatopora hystrix .

Material examined: INDONESIA: Sumatra, Siberut Island , BPBM 37647 , 4 : 15.5–23.3 mm . Sulawesi, Ujungpadang, TAU P.6305, 5: 25.5–29.0 mm. PHILIPPINES: Cebu , TAU P.3406, 2: 23.0–25.0 mm. PAPUA NEW GUINEA: Madang , AMS I.33355-001, 5: 14.3–28.0 mm (paratypes) ; BPBM 32492 , 7 : 17.0– 23.6 mm ; CAS 63655, 18.4 mm ; NTM S.13677-005, 3: 15.0–21.0 mm; USNM 323788 , 5 : 18.9–28.3 mm (paratypes) ; WAM P.30337-002, 7: 18.8–30.5 mm (paratypes) ; WAM 30337-009 , 28.5 mm (holotype) ; WAM P.30372-004, 8: 16.8–26.8 mm (paratypes) ; WAM P.30375-002, 24: 10.7–21.4 mm (paratypes) . MALAYSIA, SABAH: Mamutik Island , off Kota Kinabalu , WAM P.30402-005, 5: 17.3–20.4 mm (paratypes) . Tetagan Island, Bodgaya Islands , WAM P.30405-014, 30.0 mm (paratype) . Darvel Bay , USNM 203781 , 10 : 16.8–24.9 mm ; USNM 374477 , 17.7 mm . TIMOR SEA: Flat Top Bank , NTM S.12333-004, 2: 11.5–16.5 mm.