Sadayoshia aludra, Macpherson, Enrique & Baba, Keiji, 2012

Macpherson, Enrique & Baba, Keiji, 2012, The squat lobsters of the genus Sadayoshia Baba, 1969 (Crustacea: Decapoda: Anomura: Munididae): new records including six new species from the Pacific Ocean, Zootaxa 3589, pp. 30-48 : 38-40

Sadayoshia aludra n. sp.

( Figs. 4 , 7 D)

Sadayoshia acroporae Macpherson & Baba 2010: 418 (in part, specimens from the Chesterfield Islands).

Material examined. Holotype: New Caledonia. Chesterfield Islands. CORAIL 2, Stn DW106, 19°09'S, 158°43'E, 62 m, 27 July 1988: ov. Ƥ 8.1 mm (MNHN-IU-2010-5351).

Paratypes: New Caledonia. Chesterfield Islands. CORAIL 2, Stn DW106, 19°09'S, 158°43'E, 62 m, 27 July 1988: 2 ov. Ƥ 8.0– 9.1 mm (MNHN-IU-2010-5352, MNHN-IU-2010-5353).—Stn DW118, 19°25'S, 158°28'E, 52 m, 28 July 1988: 1 ov. Ƥ 6.8 mm (MNHN-IU-2010-5354).—Stn DW165, 19°41'S, 158°22'E, 45 m, 2 August 1988: 1 ov. Ƥ 6.9 mm (MNHN-IU-2010-5355).

Etymology. The name aludra refers to one of the stars of the southern hemisphere (constellation Canis Major). The name is considered as a substantive in apposition.

Description. Carapace: As long as broad; dorsal surface nearly horizontal from anterior to posterior; cervical groove distinct. Dorsal surface with 4 pairs of epigastric spines, 1 parahepatic, 1 anterior branchial, and 1 postcervical spine on each side; ridges with numerous short setae and scattered long iridescent setae. Gastric region with numerous transverse ridges behind epigastric spines, 8 or 9 uninterrupted ridges and 3 or 4 scale-like or interrupted ridges. Mid-transverse ridge of carapace interrupted, preceded by cervical groove; lateral part of posterior branchial region with 10 ridges (exclusive of mid-transverse ridge and posteriormost transverse ridges directly anterior to posterior margin of carapace). Lateral margins slightly convex, with 7 spines. Rostrum 1.3 times as long as broad, length 0.6 times that of carapace; rostral spine 4.5 times longer than wide (measured at sinus between rostral and anterior lateral spines), dorsal surface horizontal in lateral view, convex from side to side, with numerous short setiferous striae. Pterygostomian flap rugose with sparse setae, anterior margin ending in acute spine.

Sternum: As long as broad, lateral limits divergent posteriorly. Sternite 3 1.9 times broader than long, anterior margin slightly convex, with small but distinct median notch. Sternite 4 2.2 times longer and 3.1 times broader than preceding sternite, 0.4 times as long as broad. Surface of sternites 3-7 with some short ridges. Lateral parts of sternite 7 with some granules.

Abdomen: Somite 2 with 2 submedian spines on anterior transverse ridge; somites 2–3 with 5 uninterrupted or interrupted ridges in addition to uninterrupted anterior ridge.

Eyes: Ocular peduncles short; cornea dilated, maximum corneal diameter about 0.4 times distance between bases of anterolateral spines; eyelashes long, exceeding midlength of cornea.

Antennule: Article 1 with 4 distal spines: mesial smaller than medioventral, and clearly smaller than mediodorsal and lateral; lateral margin unarmed; ventral surface with numerous scale-like, setiferous ridges.

Antenna: Article 1 with distomesial spine slightly exceeding distal margin of article 2. Article 2 with distolateral spine longer than distomesial spine and nearly reaching end of article 3. Articles 3 and 4 unarmed.

Mxp 3: Ischium with small distal spine on flexor margin; extensor margin distally produced to distinct spine; crista dentata with 28–30 denticles. Merus subequal in length to ischium, with 2 or 3 spines on flexor margin, distal terminal, median occasionally obsolete, proximal slightly larger than distal; extensor margin unarmed. Carpus unarmed.

P1: About twice carapace length, with numerous long uniramous iridescent setae along lateral and mesial margins of merus, palm and fingers; dorsal and ventral surfaces with numerous scales bearing short setae. Merus 0.8 times length of carapace, 2.3 times as long as carpus, with strong distal spines on lateral and mesial margins, and a few additional spines on dorsal surface. Carpus 1.6 times longer than broad, with spines on dorsal and lateral surfaces and well-developed spines on mesial margin, distal second prominent. Palm 1.6 times longer than broad; with dorsolateral and mesial rows of spines continued on entire margins of fixed and movable fingers, respectively; dorsal surface with row of spines. Fingers as long as palm, distally spooned.

P2–4: Relatively slender, somewhat compressed mesio-laterally, sparsely with long uniramous iridescent setae, and numerous short plumose setae. Meri successively shorter posteriorly; P2 merus 0.8 length of carapace, 3.9 times as long as broad, 1.3 times longer than P2 propodus; P3 merus 3.7 times as long as broad, 1.2 times length of P3 propodus; P4 merus 3.8 times as long as broad, 1.2 times length of P4 propodus; dorsal margins with row of proximally diminishing spines on P2–4; ventrolateral margins with a few spines, terminal spine strong; 3 or 4 spines on lateral sides of P3 and P4. Carpi with 2 or 3 spines on extensor margin, distalmost largest; flexor margins with distal spine; lateral side with 0–2 small spines. Propodi successively shorter posteriorly, each 3.9–4.5 times as long as broad; extensor margin unarmed; 1 or 2 spines on each lateral side; flexor margin with 8 or 9 slender movable spines. Dactyli subequal in length, 0.6–0.7 times length of propodi, ending in incurved, strong, sharp spine; flexor margin with 6 or 7 seta-like movable spines, each arising from low tooth.

Remarks. The new species resembles S. acroporae Baba 1972 in having a pair of spines on the abdominal somite 2 and the dorsal surface of the rostral spine not carinate but convex from side to side. However, they can be easily distinguished by the number of ridges on the carapace and abdominal somites. Sadayoshia acroporae has 4 or 5 ridges (excluding posterior transverse ridge) on the posterior branchial margin behind the mid-transverse ridge, instead of 10 ridges as in the new species. The number of transverse ridges on the abdominal somites 2–3 is 4 in S. acroporae but 6 in the new species. The antennal article 2 has the distolateral spine distinctly longer than the distomesial spine, nearly reaching the distal end of article 3 in S. aludra , whereas the distolateral spine is subequal to or slightly smaller than the distomesial spine, terminating in the midlength of article 3 in S. acroporae .

Distribution. Chesterfield Islands, at 45– 62 m.

Figures

FIGURE 4. Sadayoshia aludra n. sp., holotype, ovigerous female, 8.1 mm, Chesterfield Islands. CORAIL 2, Stn DW 106 (MNHN-IU- 2010 - 5351). A, carapace and abdomen, dorsal view; B, sternal plastron, sternites 3 and 4; C, left cephalic region, showing antennular and antennal peduncles, ventral view; D, right Mxp 3, lateral view; E, right P 1, dorsal view; F, right P 2, lateral view; G, left P 3, lateral view; H, right P 4, lateral view. Scale: A, E – H = 2 mm; B – D = 1 mm.

FIGURE 7. Rostrum, dorsal view. A, Sadayoshia acamar n. sp., ovigerous female, 5.0 mm, Chesterfield Islands, CHALCAL 1984, Stn DC 45 (MNHN-IU- 2010 - 5378). B, S. actaea n. sp., holotype, female, 3.2 mm, Lifou Island. LIFOU, Stn 1467 (MNHN-IU- 2010 - 5372). C,. S. adaro n. sp., ovigerous female, 3.9 mm, Solomon Islands. SALOMON 1, Stn DW 1744 (MNHN-IU- 2010 - 5376). D, S. aludra n. sp., ovigerous female, 9.1 mm, Chesterfield Islands. CORAIL 2, Stn DW 106 (MNHN-IU- 2010 - 5353). E, S. moorei n. sp., holotype, ovigerous female, 4.1 mm, French Polynesia, Society Islands (UF 16050) F, S. savali n. sp., ovigerous female, 5.4 mm, Lifou Island, Stn 1450. Scale = 1 mm.