Scyllarides squammosus (H. Milne Edwards, 1837) Nisto

Hidaka, Chiho, Yang, Chien-Hui & Wakabayashi, Kaori, 2022, Parascorpaena poseidon Chou and Liao 2022, Zoological Studies 61 (73), pp. 1-12 : 5-8

Scyllarides squammosus (H. Milne Edwards, 1837) Nisto

Material examined: Nisto, NSMT-Cr 30950, BL = 39 mm, CL = 14.5 mm, CW = 17 mm, TL = 9 mm.

Description: Carapace ( Fig. 3A, 3B ): Wider than longer (CW/CL 1.17) with maximum width in the middle; surface with few tubercules, entirely furnished with fine setae; anterior margin smooth, a prominent horn present at both angles; lateral margin possessing a distinct post-cervical incision, with 8 (right) to 9 (left) anterolateral and 14 (right) to 12 (left) post-lateral teeth; rostral short with blunt end; 2 prominent tubercules and 1 small tubercule on the inner and posterior edges of orbits; gastric tooth possessing 2 prominent tubercles anteriorly and 4 small setae posteriorly; cardiac tooth bearing 2 rows of prominent tubercules anteriorly and 2 rows of small setae posteriorly, cardiac ridge with small setae; 10 small setae (8 each on the right and left sides, 2 in the middle) present along the post-cervical groove; 10 small setae in a row along post-lateral teeth; 5 small setae present at middle of posterior margin.

Antennule ( Fig. 4A ): Peduncle 3-segmented with flagellated distal end; proximal segment bearing dense long setae on ventral side; second segment possessing small setae scattered; third segment almost naked; accessory flagellum 18-articulated as long as the primary flagellum; primary flagellum thicker than accessory flagellum, 15-articulated, group of aesthetascs present on articles 5–12.

Antenna ( Fig. 3A ): 4-segmented, biramous, broad, flat; proximal segment inverted triangle, anterior margin with a ridge at middle; second segment with serrated lateral margin, prominent horn at anterolateral angle, a small notch on anteromedial margin, 2 small teeth on medial margin; third segment bearing a prominent tooth on anteromedial angle; distal segment surrounded with finely serrated margins.

Mandible ( Fig. 4B ): Poorly developed, slightly asymmetrical; palp present.

Maxillule ( Fig. 4 C ): Uniramous; poorly developed; basal endite with 5 small tubercules on anterior margin; coxal endite unarmed on anterior margin, bearing 3 small setae on basal part.

Maxilla ( Fig. 4D ): Flattened; endopod slightly differentiated with 8 setae and 3 small spines on the medial margin; endites differentiated, 4 (2+2) and 7 (5+2) setae on anterior ends of coxal and basal endites, 1 and 2 setae present on the inner proximal parts of coxal and basal endites, respectively; hair-like setae lining the outer margin of scaphognathite.

First maxilliped ( Fig. 4E ): Biramous, coxa and basis undifferentiated, flattened; endopod unsegmented, smooth; exopod with 15 marginal setae on proximal part, small setae on distal end; epipod membranous, expanding posteriorly, bearing 5 long setae; 2 small setae present at the distal end of basal endite.

Second maxilliped ( Fig. 4F ): Biramous, coxa and basis undifferentiated; endopod 4-segmented with 0,1,13,0 setae; exopod incompletely segmented, longer than endopod, 2 small setae at distal end.

Third maxilliped ( Fig. 4G ): Biramous, coxa and basis differentiated; endopod 5-segmented, carpus with dense setae (~30), propodus with 14 setae, dactylus with 4 long setae on inner margin; exopod segmented, poorly developed with 7 small setae on distal end.

Pereiopods ( Fig. 5A ): Pereiopods 1–4 biramous, coxa and basis differentiated, endopods 5-segmented with almost equal length, exopods degenerated, merus and carpus bearing a prominent horn at distal end, ischium of pereiopod 2–4 with 4 small spines; Pereiopod 5 uniramous, shortest, merus possessing a prominent horn at the distal end, ischium bearing a conspicuous spine pointing posteriorly.

Pleon ( Fig. 3A, 3B ): Tergum of pleonite 1 smooth; median carina distinct on tergites of pleonites 2–5; terga of pleonites 2–3 with a few spicules, small spines on median carina, a small tooth at center of posterior margin; terga of pleonites 4–5 smooth, a large tooth present at center of posterior margin; pleura of pleonites 2–5 serrated with large tooth, 2 small spines on the medial margins of pleura.

Pleopods ( Fig. 5B ): Present on pleonites 2–5; biramous; 2 setae at medial distal angle of protopod; exopod surrounded with 35 (pleopod 1), 37 (2), 38 (3), 33 (4) long plumose natatory setae, each possessing 6 (pleopod 1), 12 (2), 14 (3), 12 (4) small plumose setae at distal end; endopod surrounded with 48 (pleopod 1), 52 (2), 48 (3), 48 (4) long plumose natatory setae, each possessing 0 (pleopod 1), 2 (2), 5 (3), 4 (4) small plumose setae at distal end, appendix interna not reaching distal end of endopod, with approximately 12 cincinnuli at the tip, a plumose seta present just beside the cincinnuli for pleopods 2 and 4.

Uropod ( Fig. 5C ): A tooth present at lateral margins of exopod and endopod; medial margin of endopod serrated.

Telson ( Fig. 5D ): A tooth present at the proximal, lateral margins.

Color ( Fig. 1 ): Body entirely transparent in live specimen except a yellow line along the anterior margin of carapace and gills in pink. Specimen preserved in ethanol entirely white with transparent body margins.

Figures

Fig. 3. Scyllarides squammosus (H. Milne Edwards, 1837), nisto. A: Body, dorsal, a pair of antennules omitted; B: Body, lateral (left), ventral side of telson in gray. Scale bar = 5 mm.

Fig. 4. Scyllarides squammosus (H. Milne Edwards, 1837), nisto. A: Antennule, right, ventrolateral; B: Mandibles, ventral; C: Maxillule, right, ventral; D: Maxilla, right, ventral; E: First maxilliped, right, dorsal; F: Second maxilliped, right, ventral; G: Third maxilliped, right, dorsal. Scale bars:A, E, G = 1 mm; B, F = 0.5 mm; C, D = 0.1 mm.

Fig. 5. Scyllarides squammosus (H. Milne Edwards, 1837), nisto. A: Pereiopods, left, ventral, degenerated exopods shown in shaded; B: Pleopod 3, right, anterior, with enlarged distal ends of pleopods 1 and 3 (a) and pleopods 2 and 4 (b); C: Telson, dorsal; D: Uropod, right, dorsal. Scale bars: A, D = 3 mm; C = 2 mm, B = 1 mm.

Fig. 1. Scyllarides squammosus (H. Milne Edwards, 1837), nisto. A: in situ, live (photographed by Hideki Abe, reproduced with permission from Wakabayashi et al. 2017a, p. 59 in which the nisto was named as Scyllarides sp.); B: fixed specimen (NSMT-Cr 30950) in 99% ethanol. Scale bar = 5 mm.