Echinopericlimenes aurorae, Marin, Ivan & Chan, Tin-Yam, 2014

Marin, Ivan & Chan, Tin-Yam, 2014, Deep water echinoid-associated pontoniine shrimp “ Periclimenes hertwigi Balss, 1913 ” species group (Crustacea: Decapoda: Caridea: Palaemonidae): species review, description of a new genus and species from Philippines, Zootaxa 3835 (3), pp. 301-324 : 312-313

Echinopericlimenes aurorae sp. nov.

( Figs. 8–11 , 14 d–f)

Material examined. Philippines: Holotype, male (pcl 7.0 mm) ( NMCR), PANGLAO 2005, stn. CA2337, 9831.59N, 123841.79E, off Cebu Island, depth 336 meters, sandy/muddy bottom, 22 May 2005. Paratypes: 1 male (pcl 7.4 mm) ( NTOU M01747 ), PANGLAO 2005, stn. CP2343, 9827.49N, 123849.49E, off Cebu Island, depth 273–302 meters, sandy/muddy bottom, 23 May 2005; 1 mature non-ovigerous female (pcl. 9.8 mm) ( NTOU M01748 ), AURORA 2007, stn. CP2695, 14°46’N 123°39.367’E, the eastern part of Luzon Island, depth 357–367 meters, 26 May 2007.

Description. Holotype, male (NMCR). Medium-sized shrimps with subcylindrical body ( Fig. 8 a, b). Carapace swollen, smooth, non pitted, with antennal and hepatic teeth; hepatic tooth larger than antennal, situated close to pterygostomial margin of carapace, with the tip overreaching it ( Figs. 8 c; 9 a–c). Rostrum long, slender, compressed, straight, turned downward, with feebly developed dorsal lamina bearing 7–8 small teeth, with the distal third of rostrum dorsally unarmed, rostral tip sharply produced; ventral margin with feebly developed lamina bearing 2 teeth situated in its distal third, the most proximal ventral rostral tooth situated anterior to the level of the most distal dorsal rostral tooth ( Fig. 8 c; 9 b, c). Orbit well developed. Pterygostomial angle rounded.

Abdominal somites smooth; pleurae of abdominal somites I–V rounded ( Fig. 8 a, b). Telson about twice as long as proximal width, narrowing distally, with 2 pairs of small dorsal marginal spines situated at 0.5 and 0.7 of telson length ( Fig. 9 d); distal margin of telson armed with 3 pairs of spines including 1 pair of short stout lateral spines, 1 pair of long slender intermediate spines and 1 pair of simple medial spines about twice shorter than intermediate spines.

Eyes ( Fig. 9 a) well developed, with large hemispherical cornea; eyestalk about as long as wide, cylindrical, widening distally (conical); with well marked accessory pigment spot posterodorsally.

Antennula ( Fig. 9 e) well developed; basal segment about twice longer than wide, with well developed stylocerite; with distolateral angle bearing large acute triangular tooth and medial convex projection (lobe); ventromesial tooth small but distinct, situated near the medial border of basal segment (fig. 9 f); intermediate segment stout, as long as wide; distal segment relatively slender, about 1.5 times as long as wide.

Antenna ( Fig. 9 g) well developed, basicerite with sharp triangular lateral tooth, overreaching the distal margin of the segment; scaphocerite wide, about twice longer than maximal width, overreaching intermediate antennular segment, distolateral tooth well developed, acute, overreaching the distal margin of the blade.

Mouthparts characteristic for the genus. Mandible robust ( Fig. 10 a), without palp; with well developed incisor process bearing 3–4 terminal teeth ( Fig. 10 b, c); molar process robust, with sharp stout distal teeth. Maxillula ( Fig. 10 d) normal, with well developed palp bearing large triangular pointed dorsal lobe ( Fig. 10 e); upper lacinia wide, slightly curved, flaring distally, with strong setae along distal margin; lower lacinia more slender, tapering distally, covered with simple setae. Maxilla ( Fig. 10 f) with well developed simple rounded palp, with slender bilobed endite furnished dorsally with long simple stiff setae; scaphognathite well developed, fringed with plumose setae. Maxilliped I ( Fig. 10 g) with fused endites furnished with simple setae, well developed exopod with normal caridean lobe fringed with plumose setae; with large, ear-shaped epipod. Maxilliped II ( Fig. 10 h) with well developed exopod; propodus with convex distolateral margin covered with slender simple setae; dactylus thin, about 5 times as long as broad, with numerous setae along distal margin; epipod square-form; without podobranch. Maxilliped III ( Fig. 10 f) robust, exopod well-developed, slightly overreaching antepenultimate segment; segments robust, penultimate segment about 4 times as long as wide; distal segment triangular, furnished with stout simple setae; epipod rounded, curved; with small arthrobranch.

Pereiopod I ( Fig. 11 a) normal, segments unarmed; coxal segment with well developed curved lobe distoventrally; basis as long as wide; ischium about 2.5 times as long as wide; merus slender, about 6 times as long as wide; carpus slender, slightly longer than merus, about 5 times as long as wide, flaring distally, with several stout simple setae at carpo-propodal articulation; palm ( Fig. 11 b) about 1.5 times as long as wide, subcylindrical; dactylus and fixed finger stout, simple, tapering distally, about 3 times as long as wide, lightly longer than palm, with entire cutting edges; fixed finger with several bunches of stout strong plumose setae along ventral margin.

Pereiopods II equal in shape and dissimilar in size ( Fig. 11 c, e), with relatively robust segments; coxal segment with well developed curved lobe distoventrally; basis about as long as wide; ischium about 3 times as long as wide, ventral margin armed with numerous minute teeth; merus about 3.5 times as long as wide, with straight margins, ventral margin armed with numerous minute teeth; carpus flaring distally, abut as long as wide, distal margin with distolateral depression, distal margin smooth and straight; palm ( Fig. 11 d, f) cylindrical, about 4 times as long as wide, with straight margins, covered with minute teeth; fingers slender, about 1.5–2 times shorter than palm, about 3 times longer than wide; polex with stout proximal tooth, distal cutting margin straight, slightly curved, with simple tip; dactylus triangular proximal tooth and concave cutting margin, with simple, curved tip.

Pereiopod III ( Fig. 11 g) with slender unarmed segments; propodus about 6 times as long as wide, with straight and smooth margins, with 5 slender spines along ventral margin, with 1 pair of long spines and a bunch of strong simple setae at distoventral angle ( Fig. 11 h); dactylus stout, about 3 times as long as wide, with straight ventral margin, with distoventral margin armed with several large triangular teeth ( Fig. 11 i), unguis simple, smooth and curved. Pereiopods III–V similar.

Pleopods normal, without specific features. Uropods ( Fig. 9 h) stout, slightly exceeding telson; distolateral margin of exopod with triangular distolateral projection and movable spine distolaterally.

Paratype male (NTOU M01747 ) generally similar to holotype male ( Fig. 9 c); rostrum with 7 small dorsal teeth ( Fig. 9 c); uropodal exopod with 2 distolateral movable spines ( Fig. 9 i). The examined non-ovigerous female (NTOU M01748 ) ( Fig. 9 a, c–g) identical to the holotype male but possesses damaged tip of rostrum ( Fig. 8 c) and feebly marked, possibly obliterated, teeth on distoventral part of dactylus of pereiopod III ( Fig. 8 g).

Remarks. The genetic difference between the examined males from Cebu (PANGLAO 2005) and the female from Luzon Island (AURORA 2007) using barcoding gene COI represents about 4.3% (see Fig. 16). Nevertheless, all examined specimens are morphologically identical; all specimens possess slender lateral tooth on basal antennular segment, species-specific rostral dentition and characteristic form of distoventral margin of dactyli of pereiopod III (see below).

Differential diagnosis. The new species possesses long slender lateral tooth on basal antennular segment clearly separating the species from E. hertwigi comb. nov. and E. calcaratus comb. nov. The new species morphologically differs from E. dentidactylus comb. nov. mainly by smaller dorsal rostral teeth and the presence of 2 small ventral rostral teeth situated anterior to the level of the most distal dorsal rostral tooth. DNA analysis using barcoding gene COI satisfied the validity of the species showing the difference between E. aurorae sp. nov. and E. dentidactylus comb. nov. about 22.8–23.7%; the genetic differences between E. aurorae sp. nov. and E. hertwigi comb. nov. is 22.8–23.7%; between E. aurorae sp. nov. and E. calcaratus comb. nov. —24.4–25.0% (see Fig. 16).

Coloration. Body and proximal segments of appendages uniformly red; white pigmentation covered dorsal surface of fingers, dorsomesial part of the palm, dorsal surface of carpus and distodorsal margin of the merus of pereiopod II; distal margins of meri, carpi, propodi and dactyli of ambulatory pereiopods white; white longitudinal band covered dorsal margin of abdominal somites II–III reaching the proxilateral part of telson ( Fig. 14 d–h).

Etymology. The species is named after the Philippines AURORA 2007 Expedition allowed collecting several specimens of this relatively rare deep-water pontoniine shrimp species.

Host. Unknown. Possibly, similar to other representatives of the genus the new species is associated with deepwater sea urchins (Echinodermata: Echinoidea).

Distribution. The species is presently known only from the type locality, the Philippines; at the depth 273–367 meters.

Figures

FIGURE 8. Echinopericlimenes aurorae sp. nov.: ovigerous female from Philippines, 357 – 367 meters (NTOU M 01748), male from Philippines, 336 m (NMCR): a, b — general body; c — rostrum and front of carapace; d, e — pereiopod II, distal segments; f — same, fingers; g — distal part of dactylus of pereiopod III.

FIGURE 9. Echinopericlimenes aurorae sp. nov., male from Philippines, 336 m (NMCR) (a, b, d — h), male from Philippines, 273 – 302 meters (NTOU M 01747) (c, i): a — rostrum and carapace, dorsal view; b, c — same, lateral view; d — telson; e — antennula; f — basal antennular segment, lateral view; g — antenna; h — uropods; i, j — distolateral angle of uropodal exopod.

FIGURE 10. Echinopericlimenes aurorae sp. nov., male from Philippines, 336 m (NMCR): a — mandible; b, c — same, incisor process; d — maxillula; e — same, palp; f — maxilla; g — maxilliped I; h — maxilliped II; i — maxilliped III.

FIGURE 11. Echinopericlimenes aurorae sp. nov., male from Philippines, 336 m (NMCR): a — pereiopod I; b — same, chela; c, d — major pereiopod II; e, f — minor pereiopod II; g — pereiopod III; h — dactylus of pereiopod III; i — same, distal part.

FIGURE 14. Echinopericlimenes dentidactylus (Bruce, 1984) comb. nov., male from Philippines, 679 – 740 m (NTOU M 01749) (a); Echinopericlimenes calcaratus (Chace & Bruce, 1993) comb. nov., non-ovigerous female from Philippines, 80 – 90 m (NTOU M 01745) (b), non-ovigerous female from Philippines, 194 m (NTOU M 01746) (c); Ecinopericlimenes aurorae sp. nov., holotype male from Philippines, 336 m (NMCR) (d, e), male from Philippines, 273 – 302 m (NTOU M 01742) (f), non-ovigerous female from Philippines, 357 – 367 m (NTOU M 01748) (g, h).