Helcogramma rhinoceros Hansen, 1986

Tashiro, Satokuni & Motomura, Hiroyuki, 2014, The Validity of Helcogramma ishigakiensis (Aoyagi, 1954) and a Synopsis of Species of Helcogramma from the Ryukyu Islands, Southern Japan (Perciformes: Tripterygiidae), Species Diversity 19, pp. 97-110 : 107-108

Helcogramma rhinoceros Hansen, 1986

[Standard Japanese name: Tengu-hebigimpo] ( Figs 5G–H , 6E ; Table 2)

Helcogramma rhinoceros Hansen, 1986: 332 , fig. 7 (left), 15 (type locality: Putic Island, Philippines); Aizawa 1997: 560, unnumbered fig. (Iriomote-jima island, Ryukyu Islands); Suzuki et al. 1998: 2, figs 1–7 (Nakano-ugan-jima and Iriomote-jima islands, Ryukyu Islands); Motomura et al. 2010: 189, fig. 436 (Yaku-shima island, Ryukyu Islands); Kato 2011: 221, unnumbered fig. (Yaku-shima island, Ryukyu Islands); Tashiro 2013: 298, unnumbered figs (Take-shima island, Ryukyu Islands); Hayashi 2013; 1283, 2098 (Yaku-shima, Amami-oshima, and Okinawajima islands, Ryukyu Islands).

Non-type material examined. 12 specimens, 21.1– 30.3 mm SL. TAKE-SHIMA ISLAND: KAUM –I . 32332, male, 26.9 mm SL, off south coast of Ombozaki , 30°48′32″N, 130°24′33″E, 5–10 m depth, KAUM Fish Team, 19 September 2010 . NAKANO-SHIMA ISLAND: KAUM –I . 63252, female, 30.3 mm SL, Nakano-shima Port , 29°50′14″N, 129°50′56″E, 17–19 m depth, S . Tashiro , 30 August 2014; KAUM –I . 63467, female, 29.4 mm SL, south side of Nakano-shima Port , 29°50′13″N, 129°51′03″E, 5 m depth, S . Tashiro , 2 September 2014 . AMAMI-OSHIMA ISLAND: KAUM –I . 57683, female, 21.2 mm SL, KAUM –I. 57729, female, 21.1 mm SL, 28°07′57″N, 129°21′07″E, 3–15 m depth, Sokaru, Setouchi, S. Tashiro et al ., 13 December 2013. YORON-JIMA ISLAND: KAUM –I . 51381, 27.2 mm SL, off Yoron Port , 27°3′40″N, 128°25′02″E, 8 m depth, S . Tashiro , 26 October 2012; KAUM –I . 51428, male, 26.8 mm SL, KAUM –I. 51465, male, 26.7 mm SL, KAUM –I. 51466, male, 23.8 SL, off Yoron Port , 27°3′40″N, 128°25′02″E, 8 m depth, S . Tashiro , 27 October 2012 . ISHIGAKI-JIMA ISLAND: NSMT-P 55449 , female, 25.2 mm SL, 23°26′60″N, 124°04′80″E, Uganzaki, K . Matsuura et al ., 24 February 1998. NAKANOUGAN-JIMA ISLAND: KPM-NI 4341 , male, 26.1 mm SL, KPM-NI 4342 , female, 23.6 mm SL, K . Yano , 28 July 1997 .

Diagnosis. A species of Helcogramma with the following combination of characters: 14–15 (modally 15) second dorsal-fin spines; 19–24 pored lateral-line scales; 10–11 third dorsal-fin rays; 4+1+4 mandibular pores; nape without scales; anterior nostril tentacle unbranched; orbital tentacle present; males with dermal prolongation on tip of snout; lower half of head (area below level of upper lip) black; narrow blue stripe running along upper lip, through ventral margin of orbit, to preopercular margin; pelvic fin, pectoral-fin base, and lower 7 pectoral-fin rays black (all color descriptions for mature males only).

Distribution. Helcogramma rhinoceros is distributed in the eastern Indian Ocean and western Pacific Ocean, where it ranges from the Andaman Sea to southern Japan, Vietnam, Indonesia, New Caledonia, and Vanuatu ( Hansen 1986; Fricke 1997; Suzuki et al. 1998). In the Ryukyu Islands, this species was collected from Take-shima, Nakanoshima, Amami-oshima, Yoron-jima, Ishigaki-jima, and Nakano-ugan-jima islands during this study and had been previously recorded from Yaku-shima ( Motomura et al. 2010) and Iriomote-jima ( Aizawa 1997) islands. It was also confirmed from Kume-jima island (KPM-NR 36216, 64513, 64515) on the basis of underwater photographs. Helcogramma rhinoceros has been usually observed near the upper or lateral surfaces of rocks, at depths of 6– 8 m.

Remarks. Mature males of Helcogramma rhinoceros can be distinguished easily from all other species of Helcogramma by their having a dermal prolongation on the tip of the snout. Females of H. rhinoceros are similar to females of H. fuscipectoris in coloration, but H. rhinoceros differs from the latter in having a simple anterior nostril tentacle (a branched tentacle in H. fuscipectoris ).

Figures

Fig. 5. Color photographs of fresh (A, C–J) and preserved (B) specimens of Helcogramma in the Ryukyu Islands. Helcogramma aquila, A, HMNH-P 9144, male, 35.0mm SL, B, HMNH-P 4409, female, 32.5mm SL; H. fuscipectoris, C, KAUM–I. 63398, male, 22.6mm SL, D, KAUM–I. 63399, female, 24.2mm SL; H. inclinata, E, KAUM–I. 29669, male, 42.5mm SL, F, KAUM–I. 30625, female, 49.2mm SL; H. rhinoceros, G, KAUM–I. 51381, male, 27.2mm SL; H, KAUM–I. 63467, female, 29.4mm SL; H. striata, I, KAUM–I. 37748, male, 38.5mm SL, J, KAUM–I. 29515, female, 33.5mm SL.

Fig. 6. Mandibular sensory pore system of species of Helcogramma in the Ryukyu Islands. A, Helcogramma aquila (HMNH-P 9148, male, 34.4mm SL); B, H. fuscipectoris (KAUM–I. 24444, male, 28.7mm SL); C, H. inclinata (KAUM–I. 6522, male, 50.9mm SL); D. H. ishigakiensis (KAUM–I. 17519, male, 50.0mm SL); E, H. rhinoceros (KAUM–I. 32332, male, 26.9mm SL); F, H. striata (KAUM–I. 30110, male, 37.1mm SL). Scale bars 2mm.