Gnatholepis thompsoni ( Jordan , 1904)

Brito, A. & Miller, P. J., 2001, Gobiid ® shes from the Cape Verde Islands, including two new species of Gobius (Teleostei: Gobioidei), Journal of Natural History 35 (2), pp. 253-277 : 255-259

Gnatholepis thompsoni ( Jordan, 1904)

( Figure 2A )

Material. Cape Verdes: 2 ll, 271 7 and 29.51 9 mm, Caleta de San Martinho, Ilha de SaÄo Tiago, 30 December 1987, A. Brito; 1, l43.01 13.0 mm, Ilha de Sa Äo Vicente, 1993, U. Schliewen; 1,l611 21 mm (RMNH), Baia das Gates (16 ss54¾N, 24ss55¾W),

Ilha de SaÄo Vicente, 22 July 1982, CANCAP; 1 m, 40.51 12.0 mm, 1998, A. Brito.

Associated material. Western Atlantic: 10 ll, 27.0 1 8.0 to 41.5 1 12.0, 10 mm, 28.5 to 42.5 1 13.0 mm, and 20 unsexed (ANSP 123774), Dowling’s Shoal, Anguilla

(18ss14¾N, 63ss05¾W); 15 ll, 23.5 1 4.8 to 32.0 1 11.0 mm and 13 mm, 17.0 1 4.5 to

37.0 1 10.7 mm (ANSP 124650), Bequia Island, Grenadines of St Vincent (13 ss00¾N,

61ss15¾W); 6 ll, 19.0 1 4.8 to 34.0 1 11.5 mm, and 2 mm, 29.0 1 8.5 and 43.0 1 14.0 mm

(ANSP 126767), Crooked Island (22 ss45¾N, 74ss10¾W), Bahamas. Ascension: 1, l 46 1 15 mm (GCRL V76:15199); 4 ll, 22 1 d to 32.5 1 11 mm, and 3 mm, 26 1 7 to

30 1 9 mm (BMNH 1979.1.5.168±174); 3 (BMNH 1979.1.5.179±181). Ghana: 2 mm,

25.5 1 8 and 30.0 1 9.0 mm (BMNH), Vernon Bank, R. Lubbock. Canary Islands:

1 m, 42.0 1 12.5 mm, Boca Cangrejo, Tenerife, 1998, A. Brito.

Generic identi W cation. Gnatholepis Bleeker, 1874 (type species Gobius anjerensis Bleeker, 1851 , by original designation and monotypy) is a tropical Indo±West Paci®c and Atlantic gobionelline genus (sensu Miller, 1973b). The Cape Verdean specimens listed above are placed in Gnatholepis , by the possession of (i) head lateral-line canal system with anterior and posterior oculoscapular and preopercular canals; (ii) anterior oculoscapular canals separate in anterior interorbit, with paired pores l, and extending to opposite anterior nostril (pores S and terminal S 1); (iii) anterior oculoscapular pores v and B absent; (iv) four transverse rows of suborbital sensory papillae before hyomandibular row b; (v) three transverse rows above row b, last near pore a; (vi) row 6i above level of rear end of hyomandibular row d; (vii) row b short, not extending anteriorly beyond vertical of rear edge of pupil; (viii) row d divided into two parts; (ix) head, opercle, and cheek covered with ctenoid scales, (x) snout short, convex in pro®le, (xi) anterior pelvic membrane (frenum) with villose free edge; (xii) lower lip with lateral dermal ¯ap more or less evident near angle of jaws; (xiii) jaw teeth with outer row enlarged, especially in lower jaw; (xiv) vertebrae 10 1 16 (including urostyle) 5 26; (xv) dorsal pterygiophore formula (3) 12210; (xvi)

two anal ®n ptergiophores before ®rst haemal arch; and (xvii) caudal skeleton with two epurals ( Miller, 1981; Akihito et al., 1988; Birdsong et al., 1988; Pezold, 1993). Speci W c identi W cation. Gnatholepis contains a number of nominal species, but only one is recognized for the Atlantic basin. This is the Goldspot Goby, Gnatholepis thompsoni , originally described from the western Atlantic, where it occurs from Florida and Bermuda through the Caribbean to northern South America ( Randall, 1968; Cervigon, 1994). More recently, Gnatholepis populations have been reported

from the oceanic islands of Ascension and St Helena ( Edwards and Glass, 1987) as well as from the West African coast ( Miller, 1990) and, most recently, from the Canaries, around Tenerife (AB, personal observation). These records have been identi®ed as G. thompsoni . Comparison of west Atlantic G. thompsoni with the Indo±West Paci®c species G. scapulostigmata Herre ( Miller, 1981 and unpublished) indicates close similarity in possession of (i) a pronounced scapular spot, more or less ocelliform; (ii) anterior fork of suborbital dark bar faint or absent, and (iii) more or less evident longitudinal streaks on body, with thinner lines. The two are separable only by (i) modal P ray count, 16 (16±18) for G. scapulostigma and 17 (16±18) for G. thompsoni ; and in coloration, with (ii) longitudinal streaks less evident

along body, and (iii) thinner suborbital bar, in thompsoni . In meristics, as indicated by the somewhat limited material, the eastern Atlantic material from the Cape Verdes and Ghana, as well as that from Ascension, corresponds in range to the larger samples of western Atlantic G. thompsoni (table 2), but tend to have more frequent occurrence of 18 rather than 17 pectoral rays. Variants with D2 I /10 rather than D2 I/11 may be less frequent in the western Atlantic (table 2; and Cervignon, 1994).

General description. See features noted under Generic and Speci W c identi W cation. Body proportions as table 3. Anterior nostril a short tube, posterior nostril porelike. Angle of jaws below anterior edge of pupil; upper lip width about one quarter of preorbital width. Teeth caniniform, outer rows in both jaws enlarged and well spaced, especially in lower jaw, and two or three inner rows of much smaller teeth; tongue bi®d; branchiostegal membrane attached along entire lateral border of isthmus.

Fins (see table 2). D1 VI (VI:4); D2 I /11 (10±11); A I /11 (10±11); P 17 (15±18); V I/5 1 I/5; C 17. In larger specimens, D1 IV and V to D2 1, D1 VI to D2

I when depressed; D2 and A rear tips over upper and lower origins of C. Interdorsal space membranous. Pectoral ®n with uppermost rays entirely within membrane. Pelvic disc complete, with deep anterior membrane having villose free edge (®gure 3D). Caudal ®n oblong, with bluntly pointed rear edge.

Scales. Body with large ctenoid scales, 30±31 in longitudinal series (table 2), nine±ten in transverse series; predorsal scales nine or ten in median series, breast six or seven in median series; scales at origin of C without enlarged lateral cteni. Nape, opercle, cheek to infraorbital row 2, and P base covered with large scales. Coloration. Preserved (®gure 2A): head and body pale brown, latter with several broad vertical dark bars, indistinct ®ne longitudinal striae, and most scales with dark mark at focus; intense dark blotch above upper origin of P typically with dense white emargination of upper border. Head with broad dark bar from eye to rear of jaw angle and extending ventrally across lower edge of cheek to branchiostegal membrane; interorbit with narrow dark transverse line; underside of head and breast densely stippled. D1 and D2 with several oblique rows of small dark marks; A uniformly dusky, lacking dark spots; C with scattered small dark marks; P with narrow horizontal dark streak across middle of base; V dark, with pale edge.

D 2 10 11 n xÅ SD SE

BA ± 8811 ±±

GR 2 30 32 10.9 0.24 0.04

AN ± 7711 ±±

AS 1 10 11 10.9 0.29 0.09

CV 1 4 5 10.8 0.40 0.19

GH ± 2211 ±±

A 10 11 n xÅ SD SE

BA 1 7 8 10.9 0.33 0.12

GR 2 29 31 10.9 0.25 0.05

AN ± 5511 ±±

AS ± 111111 ±±

CV 1 4 5 10.8 0.40 0.19

GH ± 2211 ±±

P 15 16 17 18 n xÅ SD SE BA ± 4 10 2 16 16.9 0.60 0.15 GR ± 7 43 5 55 17.0 0.47 0.06 AN ± 5 41 6 52 17.0 0.46 0.06 AS ± 1 8 7 16 17.4 0.60 0.15 CV 1 ± 4 4 9 17.2 0.92 0.31 GH ± ± 1 3 4 17.8 0.43 0.22

LL 27 28 29 30 31 n xÅ SD SE BA ± ± 2 5 1 8 29.9 0.60 0.21 AN ± 2 11 15 5 33 29.7 0.80 0.14 AS 1 1 2 2 3 9 29.6 1.34 0.45 CV ± ± ± 3 3 6 30.5 0.50 0.20 GH ± 4 ± ± ± 4 28.0 ± ±

Lateral-line system. As Generic identi W cation and ®gures 3A±C.

Biology. Distribution. Present throughout the Cape Verdes archipelago. In the eastern Atlantic, recorded from Ghana and from the islands of Ascension and St Helena ( Edwards and Glass, 1987; Miller, 1990), and recently at localities on the east and south-east coast of Tenerife, Canary Islands (AB, personal observation). In the western Atlantic, it has been found from Bermuda and Florida to the Lesser Antilles and coast of central America ( Cervigon, 1994). Habitat. At the Cape Verdes the most common sublittoral goby, found from shore to 20 m on sand and stones. A similar habitat on sand near rocks and rubble at 5 m to at least 32 m is described by Edwards and Glass (1987) for St Helena. Tenerife specimens have been found at 7±16 m on stones and rock with sand. In the western Atlantic, at the Bahamas, this species has been reported as abundant, occurring from shore to 48 m, especially at less than 10 m, on substrata of algae-covered rocks, coral, rubble and sand, excavating burrows in sand ( Randall, 1968; Bo Èhlke and Chaplin, 1968; Cervigon, 1994). In the Western Atlantic, G. thompsoni is often associated with the Bridled

Goby, Coryphopterus glaucofraenum and C. tortugae (Cervignon, 1994) , although neither of the latter has yet been found in the eastern Atlantic. Feeding appears to involve sorting of sand in the buccal cavity and ejection of the latter from the gill openings ( Bohlke and Chaplin, 1968). Size. The largest Cape Verdean example is a male, 61 1 21 mm; with maximum values of 58 and 76 mm for standard and total length noted by Cervigon (1994).

Figures

FIG. 2. (A) Gnatholepis thompsoni, male, 43.01 13.0mm, SaÄo Vicente; (B) Gobius ateriformis sp. nov., holotype, male, 55.0 1 12.0mm (BMNH), SaÄo Tiago; (C) Mauligobius nigri, female, 70.0 1 16.0mm, SaÄo Tiago.