Plesionika crosnieri Chan & Yu, 1991

Jiang, Guo-Chen, Landeira, José M., Shih, Tung-Wei & Chan, Tin-Yam, 2018, First zoeal stage of Plesionika crosnieri Chan & Yu, 1991, P. ortmanni Doflein, 1902, and P. semilaevis Bate, 1888, with remarks on the early larvae of Plesionika Bate, 1888 (Crustacea, Decapoda), Zootaxa 4532 (3), pp. 385-395 : 387

Plesionika crosnieri Chan & Yu, 1991

( Fig. 1 )

Zoea I. Size: CL, 0.34 mm (0.27-0.48 mm); TL, 2.60 mm (2.44-2.97 mm). (n = 10)

Carapace ( Fig. 1A, B, D ): Slightly dorsoventrally flattened; rostrum slightly curved and slender, longer than antennular peduncle; dorsal anterior and posterior processes present; anteroventral margin bearing 1 strong pterygostomian spine and 3 denticles; eyes sessile.

Antennule ( Fig. 1E ): Peduncle unsegmented, slender, and bearing 1 small tubercle; endopod with 1 long, plumose seta; exopod unsegmented with 1 spatulate seta, 3 aesthetascs, 1 plumose seta.

Antenna ( Fig. 1F ): Peduncle unsegmented with 1 sharp basal spine distally; endopod unsegmented, with 1 long plumose seta and 1 sharp, slender spine terminally; exopod 6-segmented, 9 plumose setae on inner margin, 1 seta on apex and 2 plumose setae on outer margin, 1 tubercle on the first segment at proximal position in the inner margin.

Mandible ( Fig. 1G ): Palp absent; right and left slightly asymmetrical, right incisor with 3 terminal teeth; left incisor with 4 teeth (1 subterminal + 3 terminal) and lacinia mobilis.

Maxillule ( Fig. 1H ): Coxal endite with 7 (2 subterminal + 5 terminal) plumose setae; basial endite with 2 strong, cuspidate setae and 3 simple setae; endopod unsegmented, with 6 setae forming 3 groups: basal group with 1 small, simple seta and 2 sparsely plumose setae; median group with 2 sparsely plumose setae; and distal group with only 1 long sparsely plumose seta; exopod absent.

Maxilla ( Fig. 1I ): Coxal endite bilobed with 9 + 4 plumose setae; basial endite bilobed with 4 + 4 plumose setae; endopod with 9 (3 + 2 + 1 + 1 + 2) setae; scaphognathite margin with 5 plumose setae.

First Maxilliped ( Fig. 1J ): Coxa with 3 plumose setae; basis with 12 plumose setae; endopod 4-segmented with 3, 1, 2, 4 (1 outer + 3 terminal) setae; exopod unsegmented, armed distally with 4 (1+3) long, plumose natatory setae.

Second Maxilliped ( Fig. 1K ): Coxa without setae; basis with 9 plumose setae; endopod 4-segmented with 3, 1, 2, 5 (1 outer + 4 terminal) setae; exopod unsegmented, armed distally with 5 (2+3) long plumose natatory setae.

Third Maxilliped ( Fig. 1L ): Coxa without setae; basis with 4 plumose setae; endopod 4-segmented with 2, 1, 2, 4 (1 outer + 3 terminal) setae; exopod unsegmented, armed distally with 5 (2+3) long plumose natatory setae.

Pereiopods: Absent.

Pleon ( Figs. 1A, C ): With 5 somites, no spines or setae.

Pleopods: Absent.

Uropod: Absent.

Telson ( Fig. 1A ): Subtriangular, posterior margin bearing row of minute spinules as well as 7 + 7 plumose setae, outermost 2 pairs only plumose on inner margin.

Figures

FIGURE 1. Zoea I of Plesionika crosnieri Chan & Yu, 1991. A) dorsal view, B) carapace lateral view, C) pleon lateral view, D) anteroventral margin of carapace, E) antennule, F) antenna, G) left mandible, H) maxillule, I) maxilla, J) first maxilliped, K) second maxilliped, L) third maxilliped.