Elacatinus phthirophagus

Sazima, Ivan, Carvalho-Filho, Alfredo & Sazima, Cristina, 2008, A new cleaner species of Elacatinus (Actinopterygii: Gobiidae) from the Southwestern Atlantic, Zootaxa 1932, pp. 27-32 : 28-31

Elacatinus phthirophagus – sp. n.

Noronha cleaner goby

( Figures 1–4 )

Elacatinus randalli , (non Böhlke & Robins, 1968), Sazima & Moura 2000: 297 –298, Figure 1 ; Guimarães et al. 2004: 2 – 4, Figure 3 ; Sazima et al. 2004: 484, Figure 1 .

Elacatinus cf. randalli, Francini-Filho & Sazima 2007: 1 –7.

Elacatinus aff. randalli, Carvalho-Filho 1999: 210 .

Type series: Holotype: ZUEC 3895, (male, 31.8 mm SL), Ressurreta, Fernando de Noronha Archipelago (03°50’S, 32°25’W), collected by L. F. Mendes, 13 July 1998. Paratypes: MZUSP 57608 (4 ind., 21.3, 23.2, 25.5 mm SL, all females, 25.7 mm SL, male - c & s), Fernando de Noronha Archipelago (03°50’S, 32°25’W), collected by R. L. Moura & R. B. Francini Filho, 11 August 1997; ZUEC 3895 (1 ind., 31.5 mm SL, male), collected with the holotype; ZUEC 6291 (8 ind., 19.5, 20.3, 20.4, 20.7, 21.0, 22.2, 23.2, 31.5 mm SL, the last a male, the remainder females, 1 c & s), Ilha do Meio, Fernando de Noronha Archipelago (03°50’S, 32°25’W), collected by R. B. Francini Filho, R. L. Moura & L. F. Mendes, 8 June 1998; ZUEC 3318 (1 ind., 23.6 mm SL, female), Ilha da Rata, Fernando de Noronha Archipelago (03°50’S, 32°25’W), collected by L. F. Mendes, 24 November 1996; CIUFES 0 893 (2 ind., 17.0– 21.5 mm SL, females), Porto de Santo Antonio, Fernando de Noronha Archipelago (03°50’S, 32°25’W), collected by I. Sazima & C. Sazima, 19 October 2004.

Comparative material: Elacatinus randalli : USNM 202372 (paratype). Elacatinus figaro : MZUSP 50859 (holotype), 46164, 49139 (paratypes), USNM 342126 (paratype), ZUEC 3027 (paratype), 2724, 3012 (cleared and stained paratypes), 2706, 2772, 2773 (non-types). Elacatinus pridisi : ZUEC 5412 (paratype). Elacatinus prochilos : USNM 202371 (paratype). Elacatinus atronasus : USNM 202374 (paratype).

Diagnosis: Elacatinus phthirophagus sp. n. differs from its congeners of the putative “ randalli-evelynae ” cleaning clade (sensu Taylor & Hellberg 2005) by the following combination of characters: mouth subterminal, pale (bright yellow in life) elliptical spot on dark snout, width of lateral pale (bright yellow in life) stripe almost equal as eye diameter (slightly narrower in live individuals), light purplish sheen (in life) extending laterally from below eye to tail origin, no blue line (in life) from below eye to end of opercular margin, teeth multiserial on the distal portion of both jaws, males with 3 enlarged and recurved teeth on dentary inner row.

Description: Morphometrics of holotype (31.8 mm SL) and 16 paratypes (17.0– 31.5 mm SL) as percent of standard length (range and mean of paratypes in brackets): head length 26.2 (24.1–28.6, 26.2); snout length 4.1 (3.5–4.7, 4.1); eye diameter 6.0 (5.4–7.6, 6.6); postorbital distance 16.1 (14.1–20.4, 16.4); body depth 17.3 (14.4–18.1, 16.1); caudal peduncle depth 11.4 (8.3–11.6, 10.4); upper jaw length 8.8 (4.6–10.8, 8.9); pectoral-fin length 20.4 (16.4–24.1, 21.7); ventral-fin length 14.8 (14.5–18.2, 16.8); caudal-fin length 17.3 (16.7– 26.7, 20.4); pale lateral stripe width 6.3 (5.8–7.5, 6.6); black lateral stripe width 4.8 (4.0–6.0, 5.1).

Body naked, elongate and slightly laterally compressed. Mouth subterminal, U-shaped. Teeth conical and slightly curved on both jaws. Premaxillary teeth progressively larger and more curved distally, multiserial (3– 5 series) on the distal third and uniserial on the proximal fourth of upper jaw. Males with 2 large recurved teeth (1.5–2 times larger than others) on premaxillary inner row. Dentary teeth progressively larger and more curved distally, multiserial (3–5) on the distal third and uniserial on the proximal fourth of jaw. Males with 3 enlarged and recurved “canines” (about 3 times larger than others) on dentary inner row. Females with no enlarged teeth on either jaw. Caudal-fin rounded to truncate. Dorsal-fin rays VII, 11 (10–11); anal-fin rays 11 (11); pectoral-fin rays 17 (15–17). Vertebrae 11+7 (c & s male and female paratypes).

Color pattern: bright yellow postocular stripe extending to the middle of caudal-fin ( Figure 2 ); bright yellow elliptical spot on blackish snout (the latter less pigmented in small juveniles); upper portion of eye bright yellow and lower part black; black lateral stripe from lower half of eye’s posterior edge to the middle of caudal-fin and more or less coincident with lateral septum (fading towards the end of caudal-fin); black dorsal stripe from middle of interorbital space extending in a curve to the anterior third of caudal-fin (in some large specimens the anterior part of this stripe is divided by a paler, grayish stripe); lower jaw and belly whitish, the anterior third of belly with a light purplish sheen; cheek and lower part of operculum to preoperculum rosy with purplish sheen; dorsal, pectoral and anal-fins, and outer border of caudal-fin pale with scattered dark chromatophores; pelvic-fin pale with no or fewer scattered chromatophores. In preservative (formalin or ethanol) the bright yellow color fades to yellowish light gray, and the rosy and purplish sheens disappear.

Etymology. From the Greek phteir, phtheiros = louse, and phagein, phagos = to eat, an allusion to this goby feeding mostly on larval, parasitic gnathiid isopods it picks from its clients.

Distribution: The new species is known only from Fernando de Noronha Archipelago (03°50’S, 32°25’W), a volcanic formation off NE Brazil, tropical Southwestern Atlantic.

Remarks: Elacatinus phthirophagus sp. n. likely belongs in the “ randalli-evelynae ” cleaning clade (sensu Taylor & Hellberg 2005), since it shares characteristics of the species in this clade such as cleaning behavior and a pale stripe running from eye to tail. The new species is readily distinguished from Elacatinus evelynae (Böhlke & Robins) , Elacatinus genie (Böhlke & Robins) , Elacatinus illecebrosus (Böhlke & Robins) , and Elacatinus oceanops (Böhlke & Robins) by subterminal mouth (inferior, “shark-like” in the four latter species). From Elacatinus atronasus (Böhlke & Robins) and Elacatinus prochilos (Böhlke & Robins) , the new species differs mostly by dark snout with yellow elliptical spot (dark snout with no spot in the first species, and a V-shaped white mark in the second species). From Elacatinus pridisi Guimarães, Gasparini & Rocha , the new species differs mostly by black narrow lateral stripe never reaching abdomen (black broad lateral stripe reaching abdomen in the first species). From Elacatinus figaro , the new species differs mostly by black lateral stripe more or less coincident with lateral septum and fading towards the end of caudal-fin (black lateral stripe partly running below lateral septum to abdomen and reaching end of caudal-fin in the first species), and shorter snout (3.5–4.7 and 4.6–6.3% of SL respectively). The new species differ from the similar Elacatinus randalli by yellow lateral stripe width almost equal as eye diameter (much narrower than eye diameter in the precedent species), yellow elliptical spot on dark snout (yellow spot on light snout in the precedent species), no blue line in life from below eye to end of opercular margin (very conspicuous in the precedent species) ( Figure 3 ), and much shorter snout (3.5–4.7 and 6.7–8.7% of SL respectively).

The new species increases to three the number of cleaner gobies known in Southwestern Atlantic, one from the coast and two from oceanic islands ( Sazima et al. 1997, Guimarães et al. 2004, present paper). The recently described, oceanic Elacatinus pridisi ( Guimarães et al. 2004) likely belongs in the “ randalli-evelynae ” cleaning clade (sensu Taylor & Hellberg 2005) as well. Additionally, we suggest that Elacatinus phthirophagus sp. n. from Southwestern Atlantic and E. randalli from Northwestern Atlantic may be sister taxa.

Natural History: Elacatinus phthirophagus sp. n. is ubiquitous in the archipelago and was recorded in depths ranging 3 to 18 m. It tends cleaning stations on coral heads, sponges, and rocky substrata, with up to 15 individuals present in large stations, particularly those on sponges. This goby was recorded to clean about 30 species of fish clients (Francini-Filho & Sazima 2007, our pers. obs.), an assorted assemblage that include large carnivores such as the shark Carcharhinus perezi (Poey) ( Sazima & Moura 2000) and smaller ones such as the grouper Cephalopholis fulva Linnaeus ( Figure 4 ), besides small fishes like the planktivorous damselfish Chromis multilineata (Guichenot) and the zoobenthivorous butterflyfish Chaetodon ocellatus Bloch (Francini-Filho & Sazima 2007) . Among its unusual clients is the island octopus Octopus insularis Leite, Haimovici, Molina & Warnke ( Sazima et al. 2004, as Octopus cf. vulgaris ).

Figures

FIGURE 1: Elacatinus phthirophagus sp. n., holotype (ZUEC 3895), 31.8 mm SL (Photograph by I. Sazima).

FIGURE 2: Elacatinus phthirophagus sp. n., adult individual in natural habitat, showing dark snout and lateral bright yellow stripe (Photograph by J. P. Krajewski).

FIGURE 3: Elacatinus phthirophagus sp. n. (left) and Elacatinus randalli (right) in natural habitats, showing differences in width of yellow lateral stripe, pigmentation on snout, and absence versus presence of blue line extending from below eye to end of opercular margin (Photograph on left by J. P. Krajewski, that on right by L. A. Rocha).

FIGURE 4: Elacatinus phthirophagus sp. n. cleaning the head of the grouper Cephalopholis fulva, near a cleaning station on rocky substrate covered with incrusting algae and sponges (Photograph by I. Sazima).