Microbrotula polyactis , M. Eric Anderson, 2005

M. Eric Anderson, 2005, Three new species of Microbrotula (Teleostei: Ophidiiformes: Bythitidae) from the Indo-West Pacific., Zootaxa 1006, pp. 33-42: 38-40

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Microbrotula polyactis

sp. n.

Microbrotula polyactis  ZBK  sp. n.

(Fig. 2)

Holotype. AMS I.20779-128 (male, 40.0 mm SL), Australia, Cape York Peninsula , Queensland, north end of Tijou Reef , 13°05'S, 143°57'E, scuba, 2-25 m, AMS group, 22 Feb. 1979.GoogleMaps 

Paratypes. Indonesia: USNM 227227 (4 males, 21.4-33.4 mm SL; female, 25.4 mm SL), Ambon Island , 03°47'S, 128°06'E, scuba, 11-18 m, V.G. Springer & M. Gomon, 14 Mar. 1974.GoogleMaps  WAM P.30811-005 (female, 28.7 mm SL), Sulawesi Island, at Manado , 01°34'N, 124°55'E, scuba, 14-15 m, G. R. Allen, 3 Jun. 1994.GoogleMaps  Philippines: USNM 227221 (male, 38.7 mm SL), Negros Island, off Bais , 09°36.9'N, 123°10.1' E, scuba, 0-37 m, V. G. Springer & party, 13:15-14:00 hrs., 17 Jun. 1978.GoogleMaps  USNM 227224 (female, 26.3 mm SL; male, 32.4 mm SL), Cebu Island, Caceres Reef , scuba, 24-31 m, J. Libbey & party, 14:15- 15:15 hrs., 18 May 1979. 

Diagnosis. A species of Microbrotula  ZBK  distinguished by the following combination of characters: vertebrae 11-12 + 33-37 = 45-48; pectoral-fin rays 16-17; caudal-fin rays 7- 8; lateral scale rows 47-50; dorsal-fin origin above vertebrae 7-8; anal-fin origin below vertebrae 14-15; orbit diameter 16.0-18.7% HL; fleshy interorbital width 20.0-24.4% HL; predorsal length 34.4-39.9% SL.

Description. Counts and proportions, holotype first followed in parentheses by range of paratypes. Vertebrae 11 + 34 = 45 (11-12 + 33-37 = 45-48) dorsal-fin rays 70 (68-76); anal-fin rays 60 (53-66); caudal-fin rays 8 (7-8); pectoral-fin rays 17 (16-17); lateral scale rows 47 (47-50); horizontal scale rows, anal-fin origin to dorsal base 16 (16-17); developed gill rakers 3 (3); caniniform vomerine teeth 6 (4-6). Following proportions as percent SL: head length 28.3 (25.1-28.7); head width 13.0 (12.7-15.5); head depth 16.8 (12.6- 17.0); predorsal length 35.8 (34.4-39.9); preanal length 48.0 (44.7-57.5); prepelvic length 25.1 (20.9-25.6); body depth 16.8 (12.2-17.1); pectoral-fin length (two undamaged paratypes)16.8-19.4; pelvic-fin (three undamaged paratypes) 15.2-26.6. Following proportions as percent HL: head width 46.0 (44.1-53.4; head depth 59.3 (48.5-58.3); prepelvic length 88.9 (83.0-93.1); orbit diameter 16.8 (16.0-18.7); snout length 17.7 (15.2- 19.4); fleshy interorbital width 21.2 (20.0-24.4); body depth 59.3 (47.1-62.5); upper jaw length 50.4 (47.2-51.4); pectoral base depth 19.5 (16.6-20.8); pectoral-fin length (two undamaged paratypes) 58.5-70.8; distance symphysis of cleithra to pelvic-fin insertion 24.8 (17.7-34.3).

Head ovoid, postorbital length three times snout length; nape and snout depressed. Head much deeper than wide at occiput. Tip of snout fleshy, projecting beyond upper lip, with four low lobes under each of which lies short row of sensory papillae. Upper jaw expanded posteriorly, deeply ensheathed in long fleshy pocket that runs the length of the jaw; posteroventral corner with well developed projection. Teeth on jaws viliform, in 6-7 bands anteriorly in upper jaw, four anterior bands in lower, with short row of lateral canine teeth in lower jaw only. Caniniform vomerine teeth in two patches of 2-3 each; both patches with 3-5 minute teeth in a row in front of canines. Low, convoluted fleshy ridges on top of head, snout, cheeks and under eye. Minute unpigmented sensory papillae on head in a row under eye and another along upper jaw; uppermost courses behind eye and runs ventrally along anterior margin of preopercle; numerous scattered papillae (not in rows) on snout to occiput; three irregular rows on lower jaw. No head pores. Tube of anterior nostril little developed. Eye round, translucent orbital spectacle not reaching lens.

Body fully scaled including dorsal- and anal-fin bases, abdomen to posterior isthmus area and pectoral base, with 1-2 scale rows extending onto fin in paratypes, three rows in holotype. Scales on head extending anteriorly to interobital area, including cheeks and operculum.

Gill opening extending ventrally to vertical just in front of rear margin of upper jaw. Gill membranes united, free of isthmus posteriorly. Three developed gill rakers on lower limb of first arch; rakers slanted forward so rear margin oriented dorsally; two rows of minute denticles on rear margin; 3-4 denticulated raker plates below developed ones in paratypes, five plates in holotype. Pectoral fin on short peduncle, middle rays longest, almost reaching vertical through anus. Pelvic-fin insertion on vertical through base of pectoral peduncle; tips of fin broken off, when apressed, just before vertical through mid-pectoral fin. Dorsal-fin origin above middle of pectoral rays; above vertebra 7-8; anal-fin origin at mid-body, under vertebra 14-15. Copulatory organ with low fleshy hood immediately anterior to anal-fin origin. Inner surface of anterior end of hood encasing a simple, elongate genital papilla, posterior to which is a pair of much smaller papillae; tip of genital papilla with thin, fleshy lobe.

Live coloration unknown, uniformly brown in preservative. Eye blue.

Etymology. From the Greek poluz (many) and aktiz (ray, beam) in reference to its having the highest caudal- and pectoral-fin ray counts in the genus.

Distribution. Southern Philippines to northern Cape York Peninsula, Australia, in reef areas to 37 m.


Australia, New South Wales, Sydney, Australian Museum


USA, Washington D.C., National Museum of Natural History, [formerly, United States National Museum]


Australia, Western Australia, Perth, Western Australian Museum