Elacatinus pridisi Guimarães, Gasparini & Rocha, 2004, sp. n.

Elacatinus pridisi sp. n.

Trindade cleaner goby (Figs. 1- 3)

Type series: Holotype: MNRJ 21980, 23.6 mm SL, Enseada dos Portugueses, Trindade Island (20°30'S, 29°20'W), at a depth of 5 m, collected by J. L. Gasparini, 1 April 1999. Paratypes: LBRP 5618 (2 ind., 20.2, 27.8 mm SL, larger a female, smaller undetermined), Enseada dos Portugueses, Trindade Island (20°30'S, 29°20'W), at a depth of 5 m, collected by R. Z. P. Guimarães, 10 October 1998; MBML 593 (2 ind., 20.3, 24.5 mm SL, larger a female, smaller undetermined), MNRJ 21981 (2 ind., 20.2, 20.5 mm SL, undetermined), USNM 365990 (1 ind., 21.0 mm SL, undetermined), collected with the holotype; UFES 1424 (1 ind., 28.4 mm SL, undetermined), ZUEC 5412 (1 ind., 18.1 mm SL, undetermined), Enseada dos Portugueses, Trindade Island (20°30'S, 29°20'W), at a depth of 6 m, collected by J. L. Gasparini, 8th April 2001.

Additional material: LBRP 5618 (1 ind., 27.7 mm SL, c & s), Enseada dos Portugueses, Trindade Island (20°30'S, 29°20'W), at a depth of 5 m, collected by R. Z. P. Guimaráes, 10th October 1998.

Comparative material: Elacatinus randalli: ANSP 110672 (1 ind., 21.1 mm SL, holotype), ANSP 110673 (5 ind., 19.0-27.5 mm SL, paratypes), St. Vincent Islands; ANSP 110679 (1 ind., 27.3 mm SL, paratype), ANSP 110680 (3 ind., 10.5-31.5 mm SL, paratypes), Venezuela; MNRJ 12054 (2 ind.,19.8-23.4 mm SL 122.9 mm SL, c & s), Fernando de Noronha Archipelago. Elacatinus figaro: LBRP 0494 (3 ind., 21-37.7 mm SL), LBRP 0728 (7 ind., 24-30.75 mm SL, 2 ind., 24.2-27.5 mm SL c & s), LBRP 3084 (1 ind.36.7 mm SL), LBRP 3494 (20 ind.26.1-30.0 mm SL), LBRP 3515 (12 ind., 24.7-30.8 mm SL, 3 ind., 26-28.2 mm SL, c & s), state of Rio de Janeiro, Brazil.

Diagnosis: Elacatinus pridisi n. sp. differs from its congeners of the Horsti Complex (sensu Böhlke & Robins 1968) that have a pale stripe extending from the eye to the caudal-fin base by the following combination of characters: dark longitudinal stripe wide, reaching lower abdomen and base of anal fin (vs. never reaching abdomen or base of anal fin in all other species); pectoral-fin rays typically 18 (vs. typically 17 in E. randalli and E. figaro and typically 16 in E. atronasum (Böhlke & Robins)); anal-fin rays typically 11 (vs. typically 10 in E. figaro); oval spot present on snout (vs. no spot in E. atronasum and E. horsti (Böhlke & Robins), a "V"-shaped spot in E. prochilos (Böhlke & Robins), and a medial bar in E. xanthiprora (Böhlke & Robins), E. louisae (Böhlke & Robins) and E. lori Colin).

Description. Morphometrics of holotype and four largest paratype specimens (21.0-28.4 mm SL) as percent of standard length (mean): head length 22.5-24.7 (23.3); snout length 3.7-4.2(3.9); eye diameter 6.0-6.8(6.3); postorbital distance 13.5-14.9(14.3); depth of body at dorsal fin origin 15.5-16.1(15.7); least depth of caudal peduncle 11.0-12.3(11.4); upper jaw length 6.5-8.4(7.6); pectoral fin length 19.3-20.8(20.0); ventral fin length 17.3-18.3(17.7); caudal fin length 17.1-20.0(17.7); maximum width of color stripe 5.1-6.4(5.8).

Body naked, elongate. Mouth subterminal, no canine teeth on jaws. Dorsal fin without elongated anterior spines. Caudal fin rounded and ventral fin cup complete. Dorsal-fin rays VII, 11-12 (modally 12); Anal-fin rays 11; pectoral-fin rays 17-18 (modally18).

Color pattern: a pale (bright yellow in life) stripe extending from the eye to the caudal-fin base, stripe narrower close to eye (more uniform in juveniles); a pale (bright yellow in life) oval spot present on snout; dark longitudinal stripe wide, reaching lower abdomen and base of anal fin; all fin-rays except caudal black or dusky.

Remarks: Elacatinus pridisi differs from the other two Brazilian species of the genus by its higher number of pectoral-fin rays and by its wider extension of its dark pigmentation, reaching the abdomen as well as dorsal and anal-fin rays (Figure 3).

Distribution: The new species was collected only from Trindade Island (20°30'S, 29°20'W), a volcanic formation off southeastern Brazil (Figure 4) and is probably endemic to the Trindade-Martin Vaz oceanic insular complex (Figure 5).

Etymology: The name pridisi is used in honor of the Brazilian Navy First District (Primeiro Distrito Naval, Marinha do Brasil - "PRIDIS"), in recognition for the impeccable logistic support provided during the authors' field trips to the type locality.

Natural History: Elacatinus pridisi was recorded at depths ranging from 3 to 30 m over crustose algal reefs and rocky bottoms around Trindade Island. The new species performs cleaning activities during most of its life-cycle, and has, at least, 21 different client species (Gasparini & Floeter, 2001).