Uroptychus cartesi, Baba & Macpherson, 2012

Baba, Keiji & Macpherson, Enrique, 2012, A new squat lobster (Crustacea: Decapoda: Anomura: Chirostylidae) from off NW Spain, Zootaxa 3224 (1), pp. 49-56 : 50-55

Uroptychus cartesi , new species

( Figs. 1–3 )

Type material. Holotype: male (4.9 mm), ICMD-20111017-01, Bank of Galicia, off NW Spain, “INDEMARES” Station DR 15, 42º28.807'N, 011º50.028'W, 1410 m, 8 August 2011 . Paratypes: 1 male (6.0 mm), 2 ovigerous females (5.1, 5.3 mm), 1 female with egg exuvia on pleopod 3 (5.4 mm), ICMD-20111017-02, and 1 male (6.9 mm), 1 ovigerous female (6.3 mm), MNHN-IU-2009-579, station data as for the holotype .

Description. Carapace: 0.94–0.96 [0.91] (males), 0.87–0.91 (females) times as long as broad. Dorsal surface moderately convex from side to side, feebly so from anterior to posterior, with feeble depression between gastric and cardiac regions; sparingly, finely granulose, with sparse short setae. Denticle-like tiny spine on hepatic region posterior and mesial to anterolateral spine. Epigastric region with denticles transversely arranged in several small arcs (more distinct in larger specimens). Lateral margins weakly, convexly divergent posteriorly; anterolateral spine well developed, directed straight forward, overreaching article 2 of antenna; branchial margin with row of spines, anteriormost situated at anterior end, small but distinct, preceded by 2–4 [3] spines (between anterolateral spine and first branchial marginal spine) distinctly ventral to level of row, followed by 1 or [2] smaller spines on anterior branchial region and 4 moderate-sized, posteriorly diminishing spines on posterior branchial margin, last [small] or not spiniform but obtusely produced, followed by concave, ridged margin. Rostrum triangular, with interior angle of 30–[33]°, nearly horizontal, ending in sharp tip; dorsal surface feebly excavated; lateral margin with 1–3 [2 or 3] tiny spines distally; length 0.50–0.54 [0.53] that of carapace. Lateral orbital angle rounded (one female paratype), with very small (one female paratype) or moderately small spine (holotype and other paratypes), clearly smaller than anterolateral spine. Pterygostomian flap with several denticles roughly in longitudinal row on surface, anteriorly ending in small spine directed somewhat upward.

Sternum: Sternal plastron 1.1 times longer than broad; lateral extremities slightly divergent posteriorly. Excavated sternum (sternites 1–3) with convex anterior margin, surface with weak median ridge. Sternite 3 strongly depressed in ventral view, anterior margin [concavely excavated] or broadly V-shaped, with pair of small or obsolescent submedian spines separated by narrow U-shaped or [V-shaped] notch; anterolateral end sharp angular, lateral margin with tiny spine near lateral extremity. Sternite 4 with anterolateral margin weakly divergent posteriorly (anterior breadth 0.63–0.66 [0.64] times greatest breadth), anterolateral end rounded, bearing a few small denticles; posterolateral margin as long as anterolateral margin.

Abdomen: Unarmed. Somite 1 with distinct transverse ridge bearing setae [sparse] or moderate in density. Somite 2 also transversely ridged along anterior margin bearing sparse setae; pleural lateral margins weakly concave, weakly divergent posteriorly, rounded on both anterior and posterior ends. Pleura of somite 3 with bluntly angular posterolateral margin. Somites 4 and 5 with rounded posterolateral margin. Telson 0.49–[0.53] as long as broad; posterior plate 1.4–1.7 [1.5] times longer than, [0.8]–0.9 times as broad as anterior plate, posterior margin weakly emarginate.

Eyes: 1.5 times as long as broad, terminating in or [somewhat overreaching] midlength of rostrum, cornea not inflated, equally long and broad as remaining eyestalk.

Antennule and antenna: Ultimate article of antennule [2.7]–3.4 times longer than broad. Antennal article 2 with strong distolateral spine. Antennal scale [slightly falling short of] or reaching distal end of article 5, breadth [1.5]–1.9 times that of article 4. Articles 4 with distinct distomesial spine. Article 5 with tiny distomesial spine, length 1.7–2.1 [1.8] times that of article 4, breadth [0.5]–0.7 that of ultimate antennular article. Flagellum consisting of 10–14 [11] segments, about 3 times length of article 5, not reaching distal end of P1 merus.

Mxp: Mxp1 with bases distinctly separated from each other. Mxp3 sparsely setose on lateral surface. Basis with 2 obsolescent denticles on mesial ridge. Ischium with 33–40 [34] denticles on crista dentata, small on distal half; flexor margin rounded distally. Merus having mesial face flattish; flexor margin well ridged along distal half bearing 4 small spines with 1 or 2 accompanying denticles, somewhat rounded on proximal half; distolateral spine distinct. Carpus with small distolateral spine.

P1: Relatively slender, [4.0]–4.6 (males), 3.8–4.2 (females) times longer than carapace, sparsely tuberculate or granulose bearing setae, subcylindrical but palm and fingers somewhat depressed. Ischium dorsally bearing short triangular, somewhat dorsoventrally depressed spine, ventromesially bearing well-developed subterminal spine proximally followed by a few [4] denticle-like spines. Merus [0.9]–1.0 times as long as carapace, mesially with strong spine at midlength proximally followed by 1 or [2] smaller spines; ventral surface with 2 small spines mesial to midline, terminal margin mesially bearing 1 dorsal and 1 ventral spine, laterally 1 ventral spine. Carpus [1.1] – 1.2 times longer than merus, terminal margin mesially bearing 1 dorsal and 1 ventral spine, laterally 1 ventral spine; 4 protuberances on dorsal surface in close proximity to juncture with merus. Palm 1.0 (males), 0.9 (females) times as long as carpus, [3.1]–3.4 (males), 3.3 (females) times longer than broad, somewhat depressed, 0.8 times as broad as high. Fingers ventrally horizontal in lateral view, not gaping, distally ending in incurved spine; fixed finger having opposable margin somewhat concave on proximal half, feebly so in smallest female; opposable face in males with longitudinal concavity on proximal third accommodating opposing cristiform process on movable finger when closed (visible in ventral view); in females, longitudinal concavity and cristiform process obsolescent; movable finger 0.50–[0.56] length of palm.

P2–4: Moderately thick mesio-laterally and moderately setose. Meri having dorsal margin not crested but rounded with [4]–6 small spines on P2 and P3, [3] or 4 tiny or obsolescent spines on P4, unarmed on distal end; ventral margin distally ending in spine. P3 merus 0.9–[1.0] length of P2 merus, P4 merus [0.9]–1.0 (males), 0.9 (females) length of P3 merus; breadth subequal on P2–4; length-breadth ratio, 2.7–3.1 [2.9] on P2, 2.6–3.0 [2.9] on P3, [2.5]–2.9 on P4; P2 merus 0.6 length of carapace, 0.8–0.9 length of P2 propodus; P3 merus 0.7–[0.8] length of P3 propodus; P4 merus 0.7 length of P4 propodus. Carpi subequal on P2–4, [longer on P2 than on P3 and P4] or shorter on P4 than on P2 and P3; carpus-propodus length ratio, 0.3 on P2–4; extensor margin with distinct protuberance near proximal end and small terminal spine laterally accompanying much smaller one on P2 but both obsolescent on P3 and P4 and even in some specimens on P2. Propodi successively longer posteriorly, length-breadth ratio, 4.0–4.5 [4.2] on P2, 4.3–4.8 [4.6] on P3, 4.5–5.2 [5.0] on P4; propodus-carpus length ratio, 2.8–3.2 [2.9] on P2, 3.2–[3.6] on P3, 3.1–[3.8] on P4; flexor margin in lateral view somewhat concavely curving, ending in pair of spines preceded by 0–2 [1] spines on P2, [0]–1 spine on P3, none on P4. Dactyli [shorter on P2 than on P3 and P4, subequal on P3 and P4]; subequal on P2 and P4, longer on P3; or subequal on P2–4; dactylus-carpus length ratio, [1.7]–1.9 on P2, 1.7–2.1 [2.0] on P3, 1.9–2.1 [2.0] on P4; dactylus-propodus length ratio, 0.6 on P2, 0.5–[0.6] on P3 and P4; flexor margin nearly straight, with 9–[11] proximally diminishing, moderately inclined triangular spines proximal to prominent penultimate spine, ultimate spine somewhat more slender than antepenultimate, penultimate spine sharply pointed distally, twice longer than basal breadth and twice broader than antepenultimate spine.

Number of eggs carried and egg size (female carapace length). Eight eggs, 1.23 × 1.19 mm – 1.40 × 1.28 mm (cl 6.3 mm); 6 eggs, 1.20 × 1.52 mm – 1.48 × 1.39 mm (cl 5.1 mm); 1 egg, 1.52 × 1.54 mm (cl 5.3 mm).

Color in preservative (alcohol). Orange on anterior half of carapace including rostrum, P1 except for distal half of fingers, and entire P2–4.

Etymology. The species is dedicated to Joan E. Cartes (ICM), for his important contribution to the knowledge of the deep-sea Iberian fauna.

Remarks. No close relatives of the new species are found in the eastern Atlantic. The spinose carapace lateral margin as displayed by the new species is possessed only by Uroptychus bouvieri Caullery, 1896 , but the details of their spination are different. The anterolateral spine in U. cartesi is strong, distinctly overreaching the lateral orbital spine, whereas it is subequal to, not overreaching, that spine in U. bouvieri ; also the anteriormost branchial marginal spine is distinctly smaller than the first of the posterior branchial marginal spines in U. cartesi , whereas these spines are equally strong in U. bouvieri . In addition, Uroptychus cartesi differs from U. bouvieri in the following features: the epigastric region bears denticles arranged in several small arcs instead of a pair of spines behind the eyes; the P2–4 carpi are shorter, about half to slightly more than half, instead of twice, length of the dactyli; the propodal flexor margin distally ends in a pair of spines proximally followed by 0–2 spines instead of a row of spines; the penultimate flexor marginal spine on P2–4 dactyli is twice as broad rather than equally broad as the antepenultimate spine; the P1 carpus is unarmed dorsally and mesially except for the terminal spines, instead of bearing longitudinal rows of spines, one dorsal and two mesial.

For more detailed comparison, an ovigerous female (cl 4.7 mm) (BALGIM stn CP91, off Rabat, Morocco, 34°22’N, 07°25’W, 948 m, 07 June 1984, MNHN-Ga 1878), and an ovigerous female (cl 5.1 mm) and a male (cl 3.6 mm) (INDEMARES, Stn G6, Bank of Galicia, 42º49.126'N, 011º46.592'W, 903 m) referable to U. bouvieri were examined: in these specimens, the sternal plastron is 0.7 times as long as broad, with the lateral extremities strongly divergent posteriorly; and the sternite 4 bears the anterolateral margin more than 1.5 times longer than the posterolateral margin, both being the distinctive differences from U. cartesi .

Uroptychus rubrovittatus (type, ovigerous female 10.0 mm, Bay of Biscay, 44°02’N, 9°27’E, 899 m, MNHN- Ga 514, and INDEMARES, Stn G3, Bank of Galicia, 42º38.972'N, 011º49.092'W, 785 m, were examined) and U. cartesi share the P2–4 dactyli longer than the carpi, with a prominently broad penultimate flexor marginal spine, whereas in the other three eastern Atlantic species the dactyli are as long as or shorter than the carpi, with the penultimate flexor marginal spine about as broad as the antepenultimate spine. Uroptychus cartesi is distinguished from U. rubrovittatus by the following features: the carapace lateral margin is armed with distinct multiple spines instead of an anterolateral spine only; the carapace dorsal surface is sparsely granulose with denticles on the epigastric region, instead of being very granulose and unarmed; the flexor margin of P2–4 dactyli bears 9–11 instead of about 20 spines proximal to the pronounced penultimate spine.

When compared with the western Atlantic species, U. armatus (A. Milne-Edwards, 1880) may be the closest to the new species, in that the carapace bears lateral spines, the abdominal somite 2 is weakly divergent posteriorly, and the sternal plastron bears a median notch on the excavated anterior margin (A. Milne-Edwards & Bouvier, 1897). Examination of the material now available in the Smithsonian Institution of U. armatus (male, 2.2 mm, off Havana, 182 fms, “Albatross” Stn 2349, USNM 19165; 1 ovigerous female, size not measured, off west end of Grand Bahama Island, on Madrepora , not yet registered) shows additional characters shared by the new species: the P2–4 have the propodi with only a pair of terminal spines on the flexor margin and the dactyli with a prominent penultimate spine on the flexor margin; the excavated sternum (sternites 1–3) has a convex anterior margin broadly separating Mxps 1. In U. armatus , however, the anterolateral spine is relatively small although larger than the lateral orbital spine, not so strong as to extend far beyond that spine as in U. cartesi ; the dorsal surface of the carapace is smooth, covered with long soft plumose setae; the anterior margin of the sternite 4 is 1.5 times as long as the posterolateral margin; the ultimate spine of P2–4 dactyli is much longer than the penultimate spine and much (twice) broader than the antepenultimate spine; and the antennal articles 4 and 5 are unarmed.

The carapace spination of the new species somewhat resembles that of U. intermedius (A. Milne-Edwards, 1880) from the Caribbean Sea (see A. Milne-Edwards & Bouvier 1897). However, U. intermedius is distinctive in the following features: epigastric spines are distinct; sternite 3 is much more deeply excavated on the anterior margin; P1 is spinose except for the fingers; antennal article 5 bears a strong distomesial spine; P2–4 are spinose on the dorsal or extensor borders of the meri, carpi and propodi; P2–4 carpi are subequal to the dactyli in length, and the dactyli bear a penultimate flexor marginal spine that is not prominent and is as large as the antepenultimate spine.

According to J.E. Cartes (personal communication), the haul at Station DR15 also caught gorgonacean and antipatharian corals. Very possibly the present specimens were associated with one of these corals.

Distribution. Known only from the type series from off north-west Spain, at 1410 m.

Figures

FIGURE 1. Uroptychus cartesi n. sp., holotype, male. A, carapace and anterior part of abdomen, proximal part of left P1 included, dorsal. B, same, lateral. C, sternal plastron, sternites 1–3 included, ventral. D, telson. E, left antenna, ventral. F, left Mxp3, lateral. G, same, ventral. Scales = 1 mm.

FIGURE 2. Uroptychus cartesi n. sp., holotype, male. A, Left P1, proximal part, setae omitted, ventral. B, same, distal part, dorsal. C, same, fingers, setae omitted, ventral. D, right P2, lateral. E, same, distal part, setae omitted, lateral. F, right P3, setae omitted, lateral. G, right P4, setae omitted, lateral. Scales = 1 mm.

FIGURE 3. Uroptychus cartesi n. sp., paratypes. A, anterior part of carapace, dorsal, ovigerous female (5.3 mm), B, same, ovigerous female (5.1 mm), C, right P1 fingers, opened, ventral, male (6.9 mm). D, same, closed. E, left P1 fingers, opened, ventral, ovigerous female (5.1 mm). Scales = 1 mm.