Periclimenes bathyalis, Anker, Arthur, Pachelle, Paulo P. G. & Tavares, Marcos, 2014

Anker, Arthur, Pachelle, Paulo P. G. & Tavares, Marcos, 2014, Two new species and two new records of deep-water caridean shrimps from Brazil (Decapoda: Pandalidae, Palaemonidae, Crangonidae), Zootaxa 3815 (2), pp. 263-278 : 269-273

Periclimenes bathyalis sp. nov.

( Figs. 5 , 6 )

Material examined. Southwestern Atlantic Ocean off Brazil: holotype, male (pocl 4.6 mm, rl 3.7 mm), TAAF MD 55 / BRÉSIL 1987, station 53 CB 92, depth: 360 m, 19º34’S 38º55’W, 29.V.1987 ( MZUSP 31215).

Description. Body moderately slender, slightly compressed, glabrous. Rostrum slender, straight, not ascendant or descendant, slightly overreaching 0.5 length of third article of antennular peduncle; lateral carinae weak; dorsal carina with nine acute, anteriorly directed teeth, diminishing in size towards tip, most-anterior tooth subapical, two posterior teeth situated on anterior carapace posterior to post-orbital margin; ventral rostral carina with one small tooth distinctly removed from tip; supra-orbital teeth absent; inferior orbital angle bluntly produced; antennal and hepatic teeth well developed, hepatic tooth stronger than antennal tooth, situated slightly lower and in more posterior position, antennal tooth submarginal; pterygostomial angle rounded, not protruding ( Fig. 5 a, b). Thoracic sternites moderately broad, fourth sternite with minute median tooth, fifth sternite with short lateral processes.

Abdomen with third somite not projecting posterodorsally; fifth somite short, about 0.6 length of sixth somite; sixth somite about 1.3 times longer than high; pleura of first four somites broadly rounded, that of fifth slightly produced posteriorly, but rounded; sixth somite with slightly projecting, blunt posterolateral angle and more projecting, rounded posteroventral angle ( Fig. 5 d). Telson slender, about 3.2 times as long as maximum width, slightly tapering; lateral margins straight, convergent; posterior margin rounded, about 0.5 anterior width; dorsal surface of telson with two pairs of well-developed marginal or submarginal spiniform setae inserted at about 0.5 and 0.75 telson length, respectively; posterior margin with one pair of lateral, intermediate and submedian spiniform setae; lateral spiniform setae slightly smaller than dorsal spiniform setae; intermediate spiniform setae much stouter and at least five times longer than lateral spiniform setae, each about 0.25 telson length; submedian spiniform setae more slender, about 0.4 length of intermediate spiniform setae, setulose ( Fig. 5 e, f).

Antennular peduncle with proximal article flattened dorsoventrally; stylocerite short, distally acute, not reaching 0.4 length segment; statocyst with granular statolith; distolateral angle strongly produced into stout sharp tooth, latter reaching 0.5 length of intermediate article; ventromesial margin with acute tooth; intermediate article subequal to distal article in length ( Fig. 5 a, b); lateral (= upper) flagellum distinctly biramous, rami fused for seven proximal segments, shorter ramus with three free segments and about six groups of aesthetascs. Antenna with basicerite bearing strong distolateral tooth; carpocerite about three times longer than broad, compressed, extending slight past mid-length of scaphocerite; scaphocerite extending beyond antennular peduncle, blade moderately broad, about 3.5 times as long as wide, with broadly convex anterior margin; strong distolateral tooth extending well beyond anterior margin of blade; flagellum well developed ( Fig. 5 a, g). Epistome unarmed, as illustrated ( Fig. 5 c).

Mouthparts not dissected, appearing typical of Periclimenes in external view. Third maxilliped slender, pediform; coxa feebly setose, with rounded lateral plate, without epipod; basis rounded and moderately setose ventrally, carrying slender exopod nearly reaching end of antepenultimate article; endopod slender, reaching to distal end of carpocerite in full extension; antepenultimate article (ischiomerus) feebly separated from basis, about six times as long as wide, somewhat twisted, densely setose ventrally and ventromesially; penultimate article about 0.7 length of antepenultimate article and almost same width, about four times as long as wide, densely setose; ultimate article tapering, about 0.7 of length of penultimate article, with minute terminal spinule and numerous setae, especially on mesial surface.

First pereiopod rather slender, extending beyond carpocerite by carpus and chela; coxa robust, with blunt ventromesial process, latter with few terminal setae; ischium about 0.6 of merus length, about four times as long as wide, obliquely articulated with short basis; merus slightly longer than carpus, approximately 6.3 times as long as wide, carpus slightly longer than chela, four times as long as distal width, widening distally, distoventral surface with row of stiff setae; chela with palm almost twice as long as high, slightly compressed, proximoventral surface with four rows of stiff setae forming together with setal row of carpus a well-defined carpo-propodal brush; fingers about 1.3 length of palm, straight, slightly gaping, with numerous groups of setae, especially laterally on dactylus and ventrally on pollex, with small hooked tips; cutting edges of fingers laminar and entire over distal two thirds ( Fig. 6 a).

Second pereiopods robust, elongate, asymmetrical, of subequal length but unequal thickness and with conspicuously dissimilar proportions of chelae ( Fig. 6 b, e). Major cheliped extending beyond antennular peduncle by length of carpus and chela; ischium widening distally, about three times as long as distal width, about 0.7 length of merus; merus with straight dorsal and ventral margins, 4.5 times as long as wide; carpus short, vase-shaped, conspicuously widening distally; chela with palm smooth, subcylindrical, almost four times as long as high, with smooth surface; fingers slightly less than 0.5 length of palm, robust; dactylus narrowing and curving distally, with hooked, corneous tip; cutting edge with one strong, rounded, proximal tooth and one much less pronounced, low tooth more distally; pollex thicker than dactylus, with hooked, corneous tip; cutting edge with one strong, rounded, proximal tooth fitting into deep hiatus on opposed dactylar cutting edge, and one less pronounced, low, subtriangular tooth more distally, fitting into shallow hiatus on opposed dactylar cutting edge; remaining portion of finger cutting edges straight, sharp, laminar ( Fig. 6 b-d). Minor cheliped of similar size but noticeably more slender than major cheliped; ischium slightly more than four times as long as distal width, about 0.8 length of merus; merus about 4.7 times as long as wide; carpus vase-shaped, slightly longer and more slender than that of major cheliped; chela more slender, with palm about 3.7 times as long as high and distinctly longer fingers, about 0.7 length of palm; armature on proximal portion of finger cutting edges similar to that of major cheliped, however, less pronounced ( Fig. 6 e, f).

Ambulatory pereiopods (P3–5) long, slender, with third pereiopod extending beyond carpocerite by length of propodus and dactylus. Third pereiopod with coxa and basis without specific features, sparsely setose; ischium about 0.7 of merus length, less than six times length of distal width, unarmed; merus subequal to propodus in length, about nine times as long as wide, unarmed; carpus about 0.5 length of propodus, unarmed, about 5.8 times longer than wide; propodus about 12 times as long as wide, ventral margin with seven spiniform setae becoming stronger and longer towards dactylus; distoventral angle adjacent to dactylus with five spiniform setae, two lateral and three mesial (one mesial may not be visible in lateral view); dactylus about 0.2 of propodus length, distally biunguiculate; corpus compressed, about 3.5 times longer than deep, broadest centrally; ventral margin sharp, with minute, equally sized teeth and setae sparsely present along sides; subterminal unguis triangular, subacute; terminal unguis more distinct, longer, strongly curved ventrally ( Fig. 5 i, j). Fourth pereiopod similar to third; distoventral angle of propodus adjacent to dactylus with five spiniform setae, two lateral and three mesial ( Fig. 5 k). Fifth pereiopod generally similar to third and fourth; propodus with fewer (5–6) spiniform setae on ventral margin; distoventral angle adjacent to dactylus with row of stiff setae (cleaning brush) and one spiniform seta ( Fig. 5 l, m). Second male pleopod with appendix masculina shorter than appendix interna, furnished with slender spiniform setae on apex and along margin opposed to endopod ( Fig. 5 n, o). Uropod with protopod ending in blunt posterolateral lobes; exopod about three times as long as broad; lateral margin feebly convex, with small distolateral spiniform seta adjacent to blunt tooth laterally; diaeresis sinuous, with broadly U-shaped central portion; endopod slightly exceeding exopod, at least 3.5 times as long as greatest width ( Fig. 5 p).

Colour pattern unknown.

Etymology. The specific name is derived from a combination of the Greek word bathys (deep) and the Latin word alis (pertaining to), referring to the bathyal habitat of the new species.

Distribution. Western Atlantic: presently known only from the type locality off Espírito Santo, Brazil, at a depth of 360 m.

Remarks. Periclimenes bathyalis sp. nov. is morphologically most similar to Periclimenes milleri Bruce, 1986 and Periclimenes ingressicolumbi Berggren & Svane, 1989 , both associated with deep-water echinoids in the Bahamas ( Bruce 1986; Berggren & Svane 1989). The new species differs from P. milleri by the relatively longer second article of the antennular peduncle (cf. Fig. 5 a and Bruce 1986: fig. 2B); the antennal scaphocerite with a much deeper cleft between the distolateral tooth and the blade (cf. Fig.5 a and Bruce 1986: fig. 2E); the much longer palm of the major second pereiopod (cf. Fig. 6 b, c and Bruce 1986: fig. 4F); and the more dorsal position of the hepatic tooth (cf. Fig. 5 b and Bruce 1986: fig. 2A). The new species can be distinguished from P. ingressicolumbi by the different shape and proportions of the chela of the major second pereiopod (cf. Fig. 6 b, c and Berggren & Svane 1989: fig. 4B); the much more slender propodi and dactyli of the third to fifth pereiopods (cf. Fig. 5 i, l and Berggren & Svane 1989: fig. 4F-H); the less developed hepatic tooth (cf. Fig. 5 b and Berggren & Svane 1989: fig. 2A, B); the more slender telson (cf. Fig. 5 e and Berggren & Svane 1989: fig. 2F); and the antennal scaphocerite with a much deeper cleft between the distolateral tooth and the blade (cf. Fig. 5 a and Berggren & Svane 1989: fig. 2E).

Periclimenes bathyalis sp. nov. is not morphologically close to the other western Atlantic deep-water and deeper subtidal species of Periclimenes , viz. Periclimenes tenellus (267–733 m) (see Figs. 3 , 4 ), Periclimenes pandionis Holthuis, 1951 (179 m), Periclimenes magnus Holthuis, 1951 (50 m), Periclimenes finlayi Chace, 1972 (165–274 m), Periclimenes harringtoni Lebour, 1949 (shallow subtidal to 119 m), and Periclimenes iridescens Lebour, 1949 (shallow subtidal to 183 m) (cf. Lebour 1949; Holthuis 1951; Chace 1972). Among these species, P. tenellus , P. pandionis and P. finlayi approach P. bathyalis sp. nov. in the general shape of the rostrum and second pereiopods. However, these three species can be separated by the strongly biunguiculate dactyli on the third to fifth pereiopods, proportions of the antennal scaphocerite, and several other features (cf. Holthuis 1951; Chace 1972; see also Figs. 3 , 4 ).

The ecological data for the holotype of Periclimenes bathyalis sp. nov. only indicates the collection depth (320 m) of the specimen. In common with most of the deeper water species of Periclimenes , its ecology, whether freeliving or symbiont of sessile or slowly moving marine invertebrate, remains unknown.

Figures

FIGURE 3. Periclimenes tenellus (Smith, 1882): female from REVIZEE, Transecto II, station 4, Brazil (MZUSP 24982) (a – i); female and male from TAAF stations 53, 54, off Espírito Santo, Brazil (MZUSP 31496, 31497) (j, k); male from REVIZEE, Transecto II, station 4, Brazil (MZUSP 17640) (l); a, frontal region, dorsal; b, same, lateral; c, abdomen, lateral; d, telson, dorsal; e, same, posterior margin; f, third maxilliped, lateral; g, third pereiopod, lateral; h, same, distal propodus and dactylus, lateral; i, uropod, dorsal; j, k, l, rostrum, lateral.

FIGURE 4. Periclimenes tenellus (Smith, 1882): female from REVIZEE, Transecto II, station 4, Brazil (MZUSP 24982); a, first pereiopod, lateral; b, second (major) pereiopod, mesial; c, same, carpus and chela, mesial; d, same, distal chela, lateral; e, second (minor) pereiopod, lateral; f, same, carpus and chela, mesial.

FIGURE 5. Periclimenes bathyalis sp. nov.: holotype, male from TAAF station 53, off Espírito Santo, Brazil (MZUSP 31215); a, frontal region, dorsal; b, same, lateral; c, epistome, ventral; d, abdomen, lateral; e, telson, dorsal; f, same, posterior margin; g, antenna, ventral; h, third maxilliped, lateral; i, third pereiopod, lateral; j, same, distal propodus and dactylus, lateral; k, fourth pereiopod, distal propodus and dactylus, lateral; l, fifth pereiopod, lateral; m, same, distal propodus and dactylus, lateral; n, second pleopod, lateral; o, same, detail of appendix masculina and appendix interna; p, uropod, dorsal.

FIGURE 6. Periclimenes bathyalis sp. nov.: holotype, male from TAAF station 53, off Espírito Santo, Brazil (MZUSP 31215); a, first pereiopod, lateral; b, second (major) pereiopod, lateral; c, same, carpus and chela, mesial; d, same, distal chela, lateral (setae omitted); e, second (minor) pereiopod, lateral; f, same, carpus and chela, mesial.