| Punyit Dwarfgoby | Eviota punyit |
Tornabene, Valdez & Erdmann, 2016
Here, multi-locus sequence data are coupled with observations of live colouration to recognize a new species, Eviota punyit from the Coral Triangle, Indian Ocean and Red Sea. Relaxed molecular clock divergence time estimation indicates a Pliocene origin for the new species, and the current distribution of the new species and its sister species Eviota sebreei supports a scenario of vicariance across the Indo-Pacific Barrier, followed by subsequent range expansion and overlap in the Coral Triangle. These results are consistent with the ‘centre of overlap’ hypothesis, which states that the increased diversity in the Coral Triangle is due in part to the overlapping ranges of Indian Ocean and Pacific Ocean faunas. These findings are discussed in the context of other geminate pairs of coral reef fishes separated by the Indo-Pacific Barrier.
Diagnosis: Body long and slender with distinctly pointed head; cephalic sensory pore pattern 6 (lacking NA, PITO and IT pores); in life, prominent red lateral stripe beginning on snout and extending to caudal peduncle.
Description: dorsal-fin rays VI + I,9 [9(9), 8(3)]; anal-fin rays I,8 [8(11), 7 (1)]; pectoral-fin rays 17 [15(1), 16(7), 17(3)], all unbranched; the length of fifth pelvic ray 50% (40–80%) that of fourth pelvic ray; fourth pelvic ray with 12 [11(1), 12(2), 13(3), 14(4), 15 (1)] primary branches; fourth pelvic ray with 0–1 segments between consecutive branches; pelvic-fin membranes well developed; 17 branched and 12 segmented caudal-fin rays [17/12 (6), 16/12 (1), 16/11 (2)]; lateral scale rows 24 [22(2), 23(5), 24(5)]; transverse scale rows 6 [6(7), 7(5)]; cycloid or reduced ctenoid scales on ventral surface of abdomen; first dorsal fin triangular in shape, no spines notably elongate or filamentous; genital papilla in male smooth, long and not fimbriate, extending to the base of the first or second element of the anal fin (Fig. 6); female papilla smooth and bulbous with elongated projections on lateral edges of tip, with several shorter projections medially (Fig. 6); gill opening extending to just below pectoral-fin base; cephalic sensory-pore system pattern 6 with the NA, PITO and IT pores missing, and papillae pattern C (as illustrated for E. sebreei in Lachner & Karnella, 1980)
Distribution: Eviota punyit is definitively known from Brunei Darussalam, the Banda Sea and West Papua based on photographic and genetic data presented here. Based on photographs or observations of live or freshly collected specimens, E. punyit also occurs in the Red Sea (Fig. 5; Herler & Hilgers, 2005), the Seychelles (Fig. 5; Randall & van Egmond, 1994), the Maldives (Randall & Goren, 1993), Oman (Fig. 5; Randall, 1995), Halmahera (Indonesia; G. R. Allen, pers. comm.) and the Ryukyu Islands in Japan (Fig. 5; Senou, 2004).
Ecology: Although E. punyit is broadly sympatric with E. sebreei in the Coral Triangle region and occasionally the two species co-occur on the same reefs (most notably on the shallow coastal patch reefs of Brunei Darussalam), extensive in situ observations indicate clear differences in habitat preference and behaviour between the two species. While E. sebreei is found in a variety of habitats from coastal to offshore reefs and is generally in shallow water of 1–20 m, E. punyit is found exclusively on coastal reefs with significant freshwater influx and terrigenous sedimentary input, and also seems to prefer deeper habitats (12–45 m depth). Moreover, while E. sebreei is commonly found in groups of up to 10–15 individuals, E. punyit is typically solitary or in small groups of maximally two or three individuals. Finally, although E. sebreei can be found resting rather indiscriminately on massive, submassive or foliose corals, E. punyit shows a distinct preference for large foliose coral colonies.
Etymology: This species is named punyit in honour of Pulau Punyit, Negara Brunei Darussalam, where this beautiful species was first recognized as being distinct from E. sebreei. The name is treated as a noun in apposition.
L. Tornabene, S. Valdez, M. V. Erdmann and F. L. Pezold. 2016. Multi-locus Sequence Data reveal A New Species of Coral Reef Goby (Teleostei: Gobiidae: Eviota), and Evidence of Pliocene Vicariance Across the Coral Triangle. Journal of Fish Biology. DOI: 10.1111/jfb.12947