Eleotris valadei, Mennesson & Keith, 2020

Mennesson, Marion I. & Keith, Philippe, 2020, Eleotris (Teleostei: Eleotridae) of the Indian Ocean: an overview with the description of three new species, Cybium 44 (3), pp. 185-203 : 200-202

Eleotris valadei sp. nov. Keith, Mennesson & Henriette

( Figs 1D , 2, 8; Tabs VI-VIII)

Material examined

Five males and two females collected from Mayotte, Praslin ( Seychelles), Reunion Island and Madagascar, with a size range of 45-99.3 mm SL.

Holotype. – MNHN-IC-2020-0063, male (57 mm SL), Ouroveni River , Mayotte; 06 Aug. 2019; Valade coll.; tag 14561.

Paratypes. – MNHN-IC-2020-0060, male (60.6 mm SL), Ambodiforaha River , Madagascar; Jul. 2008; diamsoi coll.; tag 12950. MNHN-IC-2020-0062, male (45 mm SL), Ouroveni River , Mayotte; 20 Apr. 2009; Feutry coll.; tag 11822. MNHN-IC-2020-0059, male (46 mm SL), Mtchangachehi , Mayotte; 12 Dec. 2003; tag 12418. MNHN-IC-2020-0061, female (48 mm SL), Ouroveni river , Mayotte; date 06 Aug. 2007; Marquet coll.; tag 11818. MNHN-IC-2020-0064, female (79.3 mm SL), Reunion Island, Dec. 2007, Zimmermann et al. coll.; tag 12409. MNHN-IC-2020-0065, male (99.3 mm SL), Nouvelle-Découverte River , Praslin, Seychelles; 21 Feb. 2020; Keith , Mennesson, Henriette et al. coll.; tag 12584 .

Non types. – MNHN-IC-1966-0959, two males (105- 110 mm), Anjanambo , Tamatave Province, Madagascar, Dec. 1962, Kiener & Therezien coll.

Diagnosis

The species is distinguished by: second, third and fourth suborbital free neuromast rows on cheek extending ventrally past horizontal row d (‘2.3.4’ pattern), row os connected with row oi at ventro-posterior margin of operculum (‘closed’ pattern); 18 pectoral fin rays; 59-64 scales in lateral series and 27-30 scales in transverse forward series.

Description

Scale counts in Eleotris valadei sp. nov. and related species are given in table VI, ray counts in table VII and morphometrics in table VIII. Below, the holotype counts are given first followed in brackets, if different, by the paratype counts.

The body is elongated. The body depth at anus is 21 (19- 24% SL) and the caudal peduncle depth is 14 (13-17% SL). Predorsal length 45 (42-49% SL) and preanal length 66 (67- 70% SL).

The head 33 (33-39 % SL) is broad and depressed, the snout is pointed. Eyes high on head. The mouth is large, as the jaw length is 12 (11-15% SL), and oblique, the posterior margin of upper jaw reaches the vertical through the two thirds of the eye. Upper and lower jaws with multiple rows of small inwardly curved teeth; larger on outer row on upper jaw and larger on inner jaw on lower jaw; a few small caniniform teeth in posterior position.

Dorsal fins VI-I,8-9; D1 separate from and slightly higher than D2; spines not elongated. Anal fin I,8-9 and directly opposite to second dorsal fin. Pelvic fins separate, I,5. Pectoral fins 18. Caudal fin pointed with 15 branched rays.

Cycloid scales on top of head, nape, cheek, operculum, pectoral fin base, prepelvic region, and abdomen. Ctenoid scales covering flanks. No lateral line canals. Scales in lateral series 63 (59-64), in predorsal series 50 (45-49). Scales in transverse back series 21 (17-20), in transverse forward series 30 (27-30) and 13 (14-15) in zigzag series.

A downward pointing spine at the posterior margin of the preoperculum is covered with skin. Gill opening is moderately broad, extending to below the preoperculum. Tubular anterior nares overhanging upper lip, posterior nares open pits.

Cephalic lateralis: Adults with five transverse suborbital free neuromast rows of which second, third and fourth suborbital free neuromast rows on cheek extending ventrally past horizontal row d (‘2.3.4’ pattern); row os connected with row oi at ventro-posterior margin of operculum (‘closed’ pattern) ( Fig. 1D ).

Urogenital papilla in females rounded, elongated and tapered in males.

Colour in life ( Fig. 8 )

Male and female similar. Top of head, top of the eye and back beige with brown freckles. Lateral part of head and body dark brown. Abdomen and gular region dark brown. Lips with dark brown with evenly spaced yellow spots. First dorsal fin with 2-3 large horizontal dark bands alternating with 2 white bands; rays with yellow to orange spotted wavy rows alternating with black. Second dorsal, anal and pelvic fins with yellow to orange spotted wavy rows alternating with black. Caudal fin dark brown, with in the superior part, at anterior position, a small beige and black striped area. Pectoral fins translucent grey, pectoral base dark brown.

Colour in preservation

Male and female similar. Head and body dark brown. Abdomen and gular region dark brown. First dorsal fin with 2-3 large horizontal dark bands alternating with 2 greyish bands; rays with greyish spots alternating with black wavy spotted rows. Second dorsal, anal and pelvic fins with greyish spots alternating with black wavy spotted rows. Caudal fin dark brown, with in the superior part, at anterior position, a small beige and black striped area. Pectoral fins greyish, pectoral base dark brown.

Comparison

Eleotris valadei differs from the other species sequenced that occur in the area studied by having a high % of divergence in COI gene (6.8-14.6%).

Eleotris valadei n. sp. differs from the other species of the Indian Ocean with a ‘2.3.4’ pattern by several characters. It differs from E. soaresi in having more scales in lateral series (59-64 versus 50-56), more scales in transverse forward series (27-30 versus 22-24), in predorsal series (45-50 versus 39-43) and in zigzag series (13-15 versus 12-13). It differs from E. diamsoi n. sp., this paper, in having 18 pectoral fin rays versus 16, more scales in transverse forward series (27-30 versus 17-23), in predorsal series (45-50 versus 36-38), and a higher body depth at dorsal fin origin (19- 24 versus 15-18).

Distribution

Currently known from Madagascar, Reunion Island, Mayotte and the Seychelles islands. It was found in Seychelles in sympatry with E. pellegrini and E. acanthopoma .

Ecology

The species is supposed to be amphidromous. It is found in the lower part of the river, near the estuary. It lives in muddy to clear rivers with sandy to gravel bottom between 0 to 5 meters in altitude. It is carnivorous.

Etymology

The name of the species honours Pierre Valade, who collected several specimens of this new species in Reunion Island and Mayotte.

Figures

Figure 1. – The five different cephalic neuromast patterns in Eleotris.

Figure 8. – Eleotris valadei n. sp., MNHN-IC-2020-0065, paratype, Nouvelle-Découverte River, Praslin, Seychelles Islands (tag 12584) (© M.I. Mennesson, P. Keith).