Engraulicypris howesi Riddin, Bills & Villet

Riddin, Megan A., Bills, I. Roger & Villet, Martin H., 2016, Phylogeographic, morphometric and taxonomic re-evaluation of the river sardine, Mesobolabrevianalis (Boulenger, 1908) (Teleostei, Cyprinidae, Chedrini), ZooKeys 641, pp. 121-150 : 136-138

Engraulicypris howesi Riddin, Bills & Villet sp. n.

Holotype.

SAIAB 201623, unsexed, SL 43 mm, "Olushandja Dam at channel outlet, Kunene River System, Namibia, 17°25'53"S 14°38'36"E, 16 April 2015, R. Bills, V. Bills & R. van Zeeventer, D-net". In 70% ethanol [SAIAB]

Paratypes.

SAIAB 39012, 11 unsexed, SL 21-43 mm, 30 May 1992, C. Hay, N. James & P. Skelton; SAIAB 78759, 7 unsexed, SL 28-37 mm, Kunene River at Hippo Pool below Ruacana Waterfall, Namibia, 17°24'24"S 14°13'1"E, 21 August 2006, E. Swartz & Kramer; SAIAB 38961, 14 unsexed, SL 29-35 mm, 27, Kunene River, Namibia, 17°38'33"S 14°21'67"E, 27 May 1992, C. Hay, N. James & P. Skelton, SAIAB 35340, 6 unsexed, 2 cleared & stained, Kunene River below Ruacana Falls, Namibia, 13 January 1991, B. van der Waal [SAIAB].

Diagnosis.

Anal fin extending over three quarters of length of caudal peduncle; caudal peduncle short; operculum entirely (not partially) shiny; body midline silver (not black); iris dark to light grey (not white); head with tubercles along lower jaw and lower head in breeding males; snout rounded; pelvic fin melanophores absent.

Morphology.

(Figs 6-8; Table 7). Maximum SL 43 mm. Body elongated; somewhat fusiform; laterally compressed. Maximum body depth midway along body. Pre-dorsal profile straight or slightly convex behind head. Head length 23% of SL; with tubercles along lower jaw and lower head. Snout rounded; short; 29% of head length. Mouth terminal; slightly crescent-shaped with long anterior side; reaching anterior border of orbit. Nostrils large; level with dorsal margin of eye; separated from orbit by less than one orbit radius. Tubular anterior naris short; adjacent to open posterior naris. Eye lateral; visible from above and below (more prominent); diameter 41% of head length. First gill arch with 8+3 gill rakers on cerato- and epibranchial arms, respectively. Gill rakers long; pointed; widely-spaced. Pharyngeal bones in four rows. Pharyngeal teeth 5,3,2,1-1,2,3,5; slender and long; falcate.

Modal fin formulae in Table 7. Fins large in relation to body size. Dorsal fin closer to caudal fin than tip of snout; more or less above origin of anal fin; length 14% of SL; posterior margin straight; rays soft; anterior-most branched fin ray longest. Pectoral fins largest; reaching 1/2 to 3/4 distance to base of pelvic fin; fin lacking lobe at base. Pelvic fins reaching 2/3 distance to base of anal fin; relatively small; pointed; fin lacking a basal lobe. Anal fin moderately long; extending 2/3 length of caudal peduncle; last unbranched ray longest. Ano-genital opening at anterior of base of anal fin. Caudal peduncle moderately long; depth half of length. Caudal fin forked; lobes pointed; upper lobe shorter.

Scales small to medium relative to body size; in regular rows; cycloid; radially striate; rounded, slightly elongate. Base of anal fin lacking sheath of scales. Lateral line present; complete; dipping sharply towards ventral at tip of pectoral fin; joins midline at posterior of caudal peduncle; scale count 51-52 (n = 2) along lateral line, 14 around caudal peduncle.

Live colouration.

(Fig. 6). Body without vertical bars or bands. Dorsum transparent brown with melanophores concentrated around dorsal fin and caudal peduncle; midline silver. Snout darker dorsally. Operculum entirely metallic silver. Iris white to light grey. Dorsal fin membrane clear; rays clear with dark melanophores. Caudal fin membrane clear; rays dark brown to black, lighter towards edge; melanophores lighter towards tip. Anal fin rays clear; membrane clear; few dark spots above origin; melanophores absent. Pectoral fin membrane clear; rays clear; first ray with few dark melanophores. Pelvic fin rays clear; membrane clear.

Preserved colouration.

(Fig. 7). Body and head orange with small dark brown spots along dorsal surface, midline and above anal fin. Scales on dorsal surface lightly pigmented. Ventral scale pigmentation less intense than dorsal. Dorsal surface of head lightly pigmented. Melanophores small, dark; grouped on rear of head, below orbit, and on lips and snout; along midline, increasing in intensity to caudal fin; browner on dorsal surface, darkening between origin of pectoral and dorsal fin; forming small dark line above anal fin. Operculum with silver sheen. Side of body with silver sheen extending from pectoral fin to anal fin origin. Membranes between fin rays white to clear towards end. Pelvic fin clear membranes and rays. Dorsal, caudal and pectoral fin membranes white to clear; rays with small, widely-spaced, melanophores fading towards edges; rays pale brown to clear.

Etymology.

This species is named in honour of Gordon John Howes (1938-2013), whose studies of the osteology of the Danioninae ( Howes 1980, 1984) laid the foundations of their modern classification. The epithet is a genitive noun.

Distribution.

Namibia, Angola: Cunene River system.

Type locality.

Olushandja Dam at channel outlet (17°25 ’53’’ S 14°38 ’36’’ E), Kunene River System, Namibia.

Biology.

Very little is known of the biology of this species. Individuals appear to favour turbid, rocky, river regions where they can gather in pockets of recirculating currents. The holotype and some paratypes were collected in the shallow, turbid Olushandja Dam in the Namibian upper reaches of the system. They feed on drifting invertebrate larvae and adults and plankton.