Siphamia fuscolineata Lachner

Gon, Ofer & Allen, Gerald R., 2012, 3294, Zootaxa 3294, pp. 1-84 : 44-45

Siphamia fuscolineata Lachner

( Figure 21)

Siphamia fuscolineata Lachner, 1953: 425 , fig. 73 (type locality, Bikini Lagoon , Marshall Islands; holotype, USNM 142231 ).

Diagnosis: Dorsal rays VII+I,9; anal rays II,8; pectoral rays 14–15 (rarely 13); lateral-line scales 11–16; median predorsal scales 4–5; total gill rakers 2–4 + 8–11= 11–15; developed gill rakers 1–2 + 8–9; gill rakers on ceratobranchial 7–8. Body depth 2.4–2.8 in SL and body width 1.9–2.4 in the depth; eye diameter 2.85–3.1 in head length; first dorsal spine 2.9–4.1 in second spine; second dorsal spine 5.35–6.65, spine of second dorsal fin 4.1–4.6, and second anal spine 5.5–7.2, all in head length; pectoral-fin length 4.5–5.3 and pelvic-fin length 4.3–4.7 in SL; caudal-peduncle length 1.5–1.7 in distance between pelvic spine insertion and anal-fin origin. Preopercular edge with 16–29 small serrations; preopercular ridge smooth. Scales mostly weakly spinoid, but some cycloid ones may be present anteriorly on body. Vomer with a single and palatines with 1–2 series of minute teeth. Light organ 1.3–2.3 in caudal peduncle length and its tip on each side of tongue bound by membrane.

Colour in life: unknown.

Colour in alcohol: body brown with numerous dark brown dots; when expanded the melanophores frequently form whole or part of three dark stripes; on the holotype (USNM 142231) the first stripe runs from above eye to end of second dorsal-fin base, the second from lateral-line origin to upper part of caudal peduncle, and the third from above pectoral-fin base to ventral part of caudal peduncle; fins pale, but base of pelvic fin dark brown; peritoneum with dense dark brown dots; intestine and stomach with smaller dark dots.

Smallest and largest specimens examined, USNM 142282, 14.4 and 28.2 mm, respectively, from Bikini Atoll.

Remarks: See Tables 1–3 for frequency distributions of pectoral-fin rays, lateral-line scales and gill rakers. The last tubed lateral-line scale of one specimen (BPBM 28749) was incomplete with the top of the tube missing. In most specimens the anterior nostril was slightly closer to the tip of the snout (excluding the upper lip) than to the posterior nostril; it was at mid-distance between the two only in a few specimens. The light organ ended at the middle of the caudal peduncle in a 14.4 mm specimen and was fully developed, extending to the base of the anterior procurrent caudal rays, in specimens longer than about 20 mm. In two males of about 21.5 mm (USNM 142281) the genital papilla was relatively large, reaching at least half the length of the first anal-fin spine.

This species is a member of the S. tubifer species group. It is most similar to S. spinicola , which has a modally higher number of tubed lateral-line scales ( Table 2) and a slightly longer light organ (1.2–1.5 in caudal peduncle length). Other similar species of this group include S. majimai , S. fraseri and S. tubifer . Siphamia majimai differs in having six spines in the first dorsal fin, and has fewer gill rakers and tubed lateral-line scales ( Tables 2, 3). The number of tubed lateral-line scales is higher in S. tubifer , but modally lower in S. fraseri ( Table 2), while the number of gill rakers is modally lower in S. tubifer and higher in S. fraseri ( Table 3). S. fuscolineata also has a shorter light organ (1.3–2.3 in caudal peduncle length).

Siphamia fuscolineata is known from the Marshall and Line islands in the central-west Pacific ( Fig. 8). It was usually collected inside the lagoon of atolls at 6– 50 m. Allen (1972) described its apparent commensal relationship with the crown-of-thorns starfish, Acanthaster planci , at Enewetak Atoll.

Material examined: MARSHALL ISLANDS: Enewetak Atoll, BPBM 19997 , 20 : 15.9–24.0 mm . Bikini Atoll, USNM 142231 , 21. 4 mm (holotype) ; USNM 142281 , 31 : 15.1–26.4 mm (paratypes) ; USNM 142282 , 15 : 14.4–28.2 mm (paratypes) . Kwajalein Atoll, BPBM 28749 , 3 : 19.5–23.5 mm . LINE ISLANDS: Fanning Island , BPBM 7798 , 14.4 mm .