Elacatinus serranilla, Randall, John E. & Lobel, Phiillip S., 2009

Randall, John E. & Lobel, Phiillip S., 2009, A literature review of the sponge-dwelling gobiid fishes of the genus Elacatinus from the western Atlantic, with description of two new Caribbean species, Zootaxa 2133, pp. 1-19 : 13-16

Elacatinus serranilla , new species

( Figs. 13–15 ; Tables 1, 4 )

Gobiosoma horsti (non Metzelaar) Caldwell, 1966: 70 ( Jamaica).

Gobiosoma xanthiprora (in part) Böhlke and Robins, 1968: 85 ( Jamaica).

Gobiosoma xanthiprora (non Böhlke & Robins) Colin, 1975: 119, figs. A–E of p. 115 ( Serranilla Bank).

Holotype: UF 230714, 34.6 mm, male, Caribbean Sea, Serranilla Bank, 15°50’N, 79°50’W, from sponge, 15 m, P.L. Colin, 4 October 1971.

Paratypes: UF 208312, 31.3 mm, Jamaica, Lime Cay (off Kingston), from sponge ( Callyspongia sp.), 24 m, J.E. Randall, 18 December 1959; UF 173088, 27.5 mm, same data as holotype (too damaged for morphometrics); USNM 394968, 32.8 mm, same data as holotype.

Diagnosis: Dorsal rays VII + I,10; anal rays I,10; pectoral rays 17–18, usually 18; no scales; body and fins covered with thick adherent mucus; mouth subterminal; tongue truncate; no rostral frenum; color in alcohol: narrow dark brown stripe extending posteriorly from upper part of eye, broadening laterally on body, and ending diffusely at midposterior end of caudal fin; a narrow dark brown stripe from base of upper lip, passing just above eye, then dorsally on body below base of dorsal and fins, and continuing into dorsal part of caudal fin; narrow zone between dark stripes pale gray-brown; body below lateral dark stripe pale graybrown; fins translucent yellowish; in life, dark stripes black, narrow pale stripe between stripes bright bluish white, and body below lateral black stripe pale bluish gray; a narrow mid-dorsal bluish white band on snout from behind upper lip to front of interorbital space.

Holotype Paratypes

UF 230714 UF 208312 USNM 394968 Description: Dorsal rays VII + I,10; anal rays I,10; dorsal and anal soft rays branched, the last to base; pectoral rays 17 (18), all branched (though not all intact); pelvic rays I,5; pelvic frenum well developed; branched caudal rays 13; upper and lower procurrent caudal rays 9; head and body entirely naked, with a thick adherent covering of mucus; gill rakers 2 + 9; vertebrae 28.

The following morphometrics are given as percentages of the standard length: body depth 21.6 (19.8–21.2); body compressed, the width 12.4 (13.4–14.8); head length 28.8 (27.4–28.4); snout length 7.2 (7.1–7.2); orbit diameter 6.4 (6.4–6.9); interorbital width 4.3 (4.2–4.5); caudal-peduncle depth 14.1 (14.0–14.1); caudal-peduncle length 18.3 (18.6–19.1).

Mouth subterminal, U-shaped when viewed ventrally, and oblique laterally, forming an angle of about 17° below horizontal axis of body; maxilla reaching from below middle of orbit to below posterior edge of orbit, the upper-jaw length 12.9 (12.4–12.8); male holotype with four stout, slightly incurved, conical teeth on each side at front of upper jaw, followed by a gap and three strongly incurved and retrorse canines; three irregular inner rows of small teeth at front of jaw, narrowing to a single row medially along side of jaw; each side of front of lower jaw with an outer row of five conical, slightly incurved teeth and an inner band of five irregular rows of small conical teeth, progressively more retrorse posteriorly, narrowing to a single row of close-set, conical teeth along side of jaw, four strongly retrorse canines medially on anterior half of side of jaw, the middle two largest; female paratype with no retrorse canines in either jaw; tongue truncate; no rostral frenum, and no mental flap.

Gill opening short, extending ventrally to level of lower edge of pectoral-fin base; gill membranes attached anteriorly to isthmus; gill filaments short and lobular; gill rakers short, the longest at angle about onethird length of longest gill filaments on first gill arch.

Anterior nostril tubular, at edge of snout above upper lip, in line with ventral edge of pupil; posterior nostril dorsoposterior, about twice as large, with an outflaring membraneous rim, and slightly above center of eye; internarial distance about equal to posterior nostril diameter; cephalic sensory pores system of eight pores as diagrammed by Lachner & Karnella (1980: fig. 4a); cephalic sensory papillae and rows of papillae on side of body essentially as described for Elacatinus colini .

Origin of first dorsal fin slightly posterior to rear base of pelvic fins, the predorsal length 34.9 (34.9–35.7); dorsal and anal spines slender and flexible; fourth dorsal spine longest (but fourth spine nearly as long), 18.8 (l7.3–18.3); last membrane of first dorsal fin reaching origin of second dorsal fin; spine of second dorsal fin 14.8 (13.1–13.4); middle dorsal soft rays longest, 20.3 (18.2–19.5); origin of anal fin slightly posterior to a vertical at below of first dorsal soft ray, the preanal length 58.3 (57.3–58.3); anal spine 10.1 (9.6–10.2); sixth to ninth anal soft ray longest and subequal, 20.3 (18.2–18.4); caudal fin rounded, 26.5 (23.0–24.4); base of pectoral fins directly posterior to and equal to height of gill opening; middle pectoral rays longest, 26.0 (25.1-26.3); origin of pelvic fins slightly posterior to rear edge of pectoral-fin base, the prepelvic length 29.5 (28.5–29.2); pelvic fins joined medially to form a disk more than twice as long as wide, the disk length 22.9 (20.3–21.7); genital papilla of holotype narrowly triangular in ventral view, nearly two-thirds orbit diameter in length.

Color of holotype in alcohol: tan with a narrow dark brown stripe extending posteriorly from middle of eye to above upper end of gill opening, then widening as a midlateral band on body, and continuing into middle of caudal fin progressively less pigmented on posterior half; a narrow dark brown band dorsally on head from base of upper lip, curving to edge of nostrils, then curving back medially to dorsal edge of eye, and passing posteriorly below dorsal fins into and converging on to caudal fin; a median, narrowly elliptical dark band from front of upper lip to anterior interorbital pore; fins pale yellowish.

Color in life as shown in Figs. 13 to 15.

Etymology: We name this species Elacatinus serranilla for the type locality, the Serranilla Bank.

Remarks: Three specimens of E. serranilla (now UF 230714) were first identified by Colin (1975: 114, figs. A–E on p. 15) as a color form of Gobiosoma (Elacatinus) xanthiprora , noting the white color of the stripe on the body and the median rostral band, in contrast to the equivalent bright yellow markings of E. xanthiprora . The count of 10 dorsal soft rays for all three specimens, and the same count for a specimen from Jamaica (UF 208312) prompted a comparison with specimens of E. xanthiprora from Florida that have 11 or 12 dorsal rays. A difference was then noted in the pectoral-fin ray count, with no overlap, 19 or 20 for E.

xanthoprora and 17 or 18 for the species we name E. serranilla . Patrick L. Colin (pers. comm.) recalls collecting the same color form as E. serranilla in the Dominican Republic, but his material was lost in shipment.

As mentioned in the Introduction, the silvery blue markings of the specimens of Elacatinus from Isla de Providencia suggest they might be the same species as E. serranilla , and the fin-ray counts do not conclusively invalidate such a decision ( Table 1). Noting that the specimens of E. serranilla seem to have longer dorsal spines and longer dorsal and anal soft rays than those from Isla de Providencia, we selected three adult male specimens from the latter locality closest in length to the three male type specimens of E. serranilla for a comparison ( Table 5 ). We conclude that the specimens from Isla de Providencia represent a different species from E. serranilla . The longer dorsal and anal rays also separate E. serranilla from E. xanthiprora .

from Isla de Providencia as percentages of the standard length.

The four type specimens from the Serranilla Bank were collected alive by Patrick L. Colin on 4 October 1971 and maintained in an aquarium at the University of Miami for “several months.” The sponge from which he collected one of the males contained a compact mass of 624 eggs at the bottom of the lumen. The male was in the dark color phase typical of a brooding goby of this genus. Plastic pipe was provided in the aquarium and accepted as shelter, as may be seen by the fish of Figs. 14 and 15 . The fish was removed for a specimen photo by Colin ( Fig. 13 ).

The gobies spawned readily in the aquarium, laying and brooding eggs within the plastic pipe. Reproductive activity, eggs, and larvae were discussed by Colin (1975). Judging from the gut contents of other sponge-dwelling species of the genus, he surmised that a large portion of the diet of this species will prove to be the parasitic sponge polychaete Haplosyolis spongicola .

We present a map as Fig. 16 showing the distribution of the species of the Elacatinus xanthiprora complex.

Figures

FIGURE 13. Holotype of Elacatinus serranilla, Serranilla Bank, Caribbean Sea (photograph by P. L. Colin).

FIGURE 14. Holotype of Elacatinus serranilla, Serranilla Bank (photograph by P. L. Colin).

FIGURE 15. Holotype of Elacatinus serranilla, Serranilla Bank (photograph by P. L. Colin).

FIGURE 16. Distribution of Elacatinus xanthiprora (yellow spots in Florida), E. colini (red spots in Belize and Islas de la Bahía), E. serranilla (blue spots at Serranilla Bank and Jamaica), E. sp. 1 (lime green spot at edge of Nicaragua continental shelf, and E. sp. 2 (magenta spot at Isla de Providencia). Basic map from R. F. Myers.

Tables

TABLE 4. Proportional measurements of type specimens of Elacatinus serranilla as percentages of the standard length.

Standard length (mm)	34.6	31.3	32.8
Sex	male	male	male
Body depth	21.6	19.8	21.2
Body width	12.4	13.4	14.8
Head length	28.8	28.4	27.4
Snout length	7.2	7.1	7.2
Orbit diameter	6.4	6.4	6.9
Interorbital width	4.3	4.5	4.2
Upper-jaw length	12.9	12.8	12.4
Caudal-peduncle depth	14.1	14.1	14.0
Caudal-peduncle length	18.3	19.1	18.6
Predorsal length	35.9	34.9	35.7
Preanal length	58.3	57.3	58.3
Prepelvic length	29.5	28.5	29.2
Base of dorsal fins	48.6	48.1	48.2
Longest dorsal spine	18.8	17.3	18.3
Spine of second dorsal fin	14.8	13.4	13.1
Longest dorsal ray	21.6	18.2	19.5
Base of anal fin	21.1	20.8	21.4
Anal spine	10.1	9.6	10.2
Longest anal ray	20.3	17.4	18.4
Caudal-fin length	26.5	23.0	24.4
Pectoral-fin length	26.0	25.1	26.3
Pelvic-disk length	22.9	20.3	21.7

TABLE 5. Comparison of selected fin measurements of male specimens of Elacatinus serranilla and Elacatinus sp.

	Elacatinus serranilla	Elacatinus sp. 2
Standard length (mm)	UF UF UF 208312 230714 230714 31.3 32.8 34.6	ANSP ANSP ANSP 112626 112623 112625 26.5 35.2 36.0
Longest dorsal spine	17.3 18.3 18.8	15.6 16.9 16.2
Longest dorsal ray Longest anal ray	18.2 19.5 21.6 17.4 18.4 20.3	17.2 17.5 17.4 15.8 17.2 16.8