Sadayoshia actaea, 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 : 34-36

Sadayoshia actaea n. sp.

( Figs. 2 , 7 B)

Sadayoshia latisternata Macpherson & Baba 2010: 433 (in part, only specimens from New Caledonia).

Material examined. Holotype: New Caledonia, Lifou Island. LIFOU, Stn 1467, 20º46.6'S, 167º05.7'E, 90 m, 20 November 2000: Ƥ 3.2 mm (MNHN-IU-2010-5372).

Paratypes: New Caledonia, Lifou Island. LIFOU, Stn DW14 Stn 1467, 20º46.6'S, 167º05.7'E, 90 m, 20 November 2000: 1 Ƥ 3.5 mm (MNHN-IU-2010-5373).

Etymology. The name actaea refers to one of the Nereids in the Greek mythology. 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. Four pairs of epigastric spines and 1 parahepatic spine on each side; 4 uninterrupted ridges on gastric region behind epigastric spines; mid-transverse ridge of carapace uninterrupted, preceded by cervical groove. Posterior branchial region laterally with 4 ridges (exclusive of mid-transverse ridge and posteriormost transverse ridges directly anterior to posterior margin of carapace). Dorsal surface with short uniramous and a scattered long setae arising from transverse ridges. Lateral margins medially convex, with 7 spines. Rostrum moderately broad, 1.1 times as long as broad, length 0.4 times that of carapace; dorsal surface nearly horizontal in lateral view, slightly convex from side to side, without setiferous striae; rostral spine 2.1 times longer than wide (measured at sinus between rostral and anterior lateral spines). Pterygostomian flap rugose with sparse setae, anterior margin ending in blunt point.

Sternum: Sternal plastron as long as broad, lateral limits divergent posteriorly. Sternite 3 3.2 times as broad as long, anterior margin moderately produced, with small V-shaped median notch. Sternite 4 2.4 times longer and twice as broad as preceding sternite, 3.9 times broader than long; surface with 1 anterior stria flanking midline. Following sternites smooth. Lateral parts of sternite 7 smooth.

Abdomen: Somite 2 unarmed; somites 2–4 without transverse ridges other than anterior one bearing both short and scattered long uniramous setae.

Eyes: Peduncle as long as broad; cornea slightly dilated; maximum corneal diameter about 0.4 times distance between bases of anterolateral spines; eyelashes short, not reaching midlength of cornea.

Antennule: Article 1 with 4 distal spines: mesial and medioventral subequal and clearly smaller than others; lateral margin unarmed; ventral surface with a few short scales.

Antenna: Article 1 with distomesial spine nearly reaching distal margin of article 2. Article 2 with distolateral spine larger than distomesial, reaching midlength of article 3. Articles 3 and 4 unarmed.

Mxp3: Ischium with small distal spine on flexor margin; extensor margin unarmed; crista dentata with 29 denticles. Merus subequal in length to ischium, flexor margin with 2 subequal small spines: distal terminal, proximal at midlength; extensor margin unarmed. Carpus unarmed.

P1: 1.2 times carapace length, stout, with long uniramous iridescent setae along lateral and mesial margins of merus, palm and fingers; dorsal and ventral surfaces of palm and fingers with scattered short setae. Merus about 0.4 times length of carapace, 2.5 times as long as carpus, with dorsal and lateral spines, and 1 strong distomesial spine. Carpus 0.5 times length of palm, 0.5 times as long as broad; with small spines on dorsal surface, 2 well-developed spines on mesial margin and a few spines along distal margin. Palm 0.8 times as long as broad; mesial and lateral margins with strong spines continued on to fingers, dorsal surface with sparse spines. Fingers distally spooned; movable finger as long as palm, dorsal surface with 2 proximal spines.

P2–4: Somewhat compressed mesio-laterally, sparsely with long uniramous iridescent setae and some short plumose setae. Meri successively shorter posteriorly; P2 merus 0.6 times carapace length, 3.0 times as long as broad, 1.4 times longer than P2 propodus; P3 merus 2.9 times as long as broad, 1.2 times length of P3 propodus; P4 merus 3.1 times as long as broad, 1.1 times length of P4 propodus; dorsal margins of meri with row of proximally diminishing spines on P2 and P3, minute spines on P4; dorsolateral surface unarmed on P2 and P3, with 2 spines on P4; ventrolateral margins with well-developed terminal spine. Carpi with 3 spines on extensor margin of P2 and P3, unarmed on P4, distalmost largest; lateral surface unarmed or with 1 spine; flexor margins with distal spine. Propodi subequal in length on P2 and P3. slightly shorter on P4, each about 3 times as long as broad; extensor margin with 1 or 2 proximal spines, lateral side unarmed; flexor margin with 5–7 slender movable spines on P2–4. Dactyli subequal in length, 0.7–0.8 times length of propodi, ending in incurved, strong, sharp spine; flexor margin with 5 or 6 obsolescent teeth, each with seta-like movable spine.

Remarks. The new species strongly resembles S. latisternata Macpherson & Baba 2010 in the relatively smooth abdominal somites 2–4 bearing only an anterior ridge and the shape of sternite 3 short relative to breadth. Sadayoshia actaea can be distinguished from S. latisternata by lacking instead of possessing the anterior branchial spine on the carapace. Furthermore, the rostral spine is about 2.0 times longer than wide (measured at sinus between rostral and anterior lateral spines) in S. actaea , whereas it is about 3 times longer in S. latisternata .

Distribution. New Caledonia, Lifou Island, at 90 m.

Figures

FIGURE 2. Sadayoshia actaea n. sp., holotype, female, 3.2 mm, Lifou Island. LIFOU, Stn 1467 (MNHN-IU- 2010 - 5372). 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, left P 1, dorsal view; F, left P 2, lateral view; G, left P 3, lateral view; H, right P 4, lateral view. Scale: A, E – H = 1 mm; B – D = 0.5 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.