Sadayoshia adaro, 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 : 36-38

Sadayoshia adaro n. sp.

( Figs. 3 , 7 C)

Sadayoshia inermis Macpherson & Baba 2010: 428 (in part, specimens from the Solomon Islands).

Sadayoshia tenuirostris Macpherson & Baba 2010: 444 (in part, only one specimen from the Solomon Islands).

Material examined. Holotype: Solomon Islands. SALOMON 1, Stn DW1822, 9°51.8'S, 160°51.8'E, 51–54 m, 0 3 October 2001: 1 Ƥ 3.6 mm (MNHN-IU-2010-5374).

Paratype: Solomon Islands. SALOMON 1, Stn DW1744, 10°32.0'S, 159°38.9'E, 49–55 m, 23 September 2001: 1 ov. Ƥ 3.9 mm (MNHN-IU-2010-5376).—Stn DW1822, 9°51.8'S, 160°51.8'E, 51–54 m, 0 3 October 2001: 1 ov. Ƥ broken (MNHN-IU-2010-5375).

Etymology. The name adaro refers to a sea-spirit in the Salomon Islands myths. 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 and 1 or 2 anterior branchial spines on each side; ridges with numerous short uniramous setae. Gastric region with 5 transverse ridges behind epigastric spines, first and third to fifth uninterrupted, second interrupted (scale-like median ridge flanked by longer ridge on each side). Mid-transverse ridge of carapace uninterrupted, preceded by cervical groove. Posterior branchial region laterally with 6 ridges (exclusive of mid-transverse ridge and posteriormost transverse ridges directly anterior to posterior margin of carapace). Lateral margins slightly or moderately convex, with 7 spines. Rostrum 1.8 times as long as broad, length 0.4 that of carapace, lateral margin with 2 spines; rostral spine 1.2 times longer than wide (measured at sinus between rostral and anterior lateral spines), dorsal surface flat, with short setiferous striae, nearly horizontal in lateral view, one minute distal tooth on each side. Pterygostomian flap rugose with sparse short ridges, ending in blunt point.

Sternum: Sternite 3 1.6 times as broad as long, anterior margin strongly convex, with small median notch. Sternite 4 1.6 times as long as and 2.7 times broader than preceding sternite, 2.7 times broader than long; surface with 2 transverse ridges, anterior medially interrupted. Sternites 4–6 with 0–2 short ridges. Lateral parts of sternite 7 without granules.

Abdomen: Somite 2 unarmed; somites 2–4 each with 4 transverse ridges, anterior first and third uninterrupted, second and fourth interrupted; ridges with numerous short setae and sparse long iridescent setae.

Eyes: Peduncles 1.4 times longer than broad; cornea moderately 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 smaller than others, lateral largest; lateral margin unarmed; ventral surface smooth.

Antenna: Article 1 with distomesial spine slightly exceeding distal margin of article 2. Article 2 with distolateral spine longer than distomesial, terminating in midlength of article 3. Articles 3 and 4 unarmed.

Mxp3: Ischium with very small distal spine on flexor margin; extensor margin bluntly produced distally; crista dentata with 23–26 denticles. Merus as long as ischium, flexor margin with 2 subequal spines, distal one terminal, proximal one at midlength; extensor margin unarmed. Carpus unarmed.

P1: 1.8 times carapace length, relatively 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 short setae. Merus 0.6 times as long as carapace, 2.2 times as long as carpus, with strong distal spines on dorsal and mesial margins, and a few additional small spines on dorsal surface. Carpus 0.7 times length of palm, and 0.9 times as long as broad; dorsal surface with spines; mesial surface with well-developed spines. Palm 0.9 times longer than broad; with dorsolateral and mesial rows of spines continued on to entire margins of fixed and movable fingers, respectively; dorsal surface with a few spines. Fingers 1.3 times as long as palm, distally spooned.

P2–4: Somewhat compressed mesio-laterally, sparsely with long uniramous iridescent setae, and short setae. Meri successively shorter posteriorly; P2 merus 0.6 times carapace length, 3.1 times as long as broad, 1.2 times longer than P2 propodus; P3 merus 2.7 times as long as broad, 1.2 times length of P3 propodus; P4 merus 3.0 times as long as broad, 1.1 times length of P4 propodus; dorsal margins with row of proximally diminishing spines on P2 and P3, nearly unarmed on P4; ventrolateral margins with strong terminal spine. Carpi with 3 extensor marginal spines distinct on P2 and P3, obsolescent on P4, distalmost larger; flexor margins with distal spine; lateral surface with 0 or 1 small spine. Propodi 3.2–3.6 times as long as broad; extensor margins with 2 proximal spines, lateral side unarmed; flexor margin with 6–8 slender movable spines. Dactyli subequal in length, 0.8–0.9 times length of propodi, ending in incurved, strong, sharp spine; flexor margin with 5 or 6 seta-like movable spines, each arising from obsolescent tooth.

Remarks. The new species is closely related to S. inermis Macpherson & Baba, 2010 , sharing the thick rostrum and the absence of postcervical spines on the carapace. However, these species can be differentiated by the shape of the rostral spine. This spine is very short and thick, being less than 2 two times longer than wide (measured at the sinus between the rostral and anterior lateral spines) in S. adaro , whereas it is 2.5–3.0 times longer in S. inermis . Furthermore, the flexor margin of the Mxp 3 usually has 2 spines in S. adaro and usually 3– or 4 spines in S. inermis .

Distribution. Solomon Islands, at 51– 54 m.

Figures

FIGURE 3. Sadayoshia adaro n. sp., holotype, female, 3.6 mm, Solomon Islands. SALOMON 1, Stn DW 1822 (MNHN-IU- 2010 - 5374). 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, right 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.