Heterocarpus hayashii Crosnier, 1988

(Fig. 2, Table 1)

Size: CL, mean 0.41 mm (range 0.38–0.45 mm); BL, mean 1.89 mm (range 1.85–1.93 mm); TL, mean 2.29 mm (range 2.25–2.33 mm).

Carapace (Figs. 2 A, B, D): Slightly dorsoventrally flattened; rostrum slightly curved and slender, longer than antennular peduncle; dorsal anterior and posterior processes present; anteroventral margin bearing strong pterygostomian spine as well as 2 distinct spines; eyes sessile.

Antennule (Fig. 2 E): Peduncle unsegmented, slender and bearing 1 small tubercle; exopod unsegmented with 1 spatulate seta and 3 terminal aesthetascs as well as 1 terminal plumose seta; endopod with 1 long plumose seta.

Antenna (Fig. 2 F): Peduncle unsegmented and with 1 distal spine; endopod unsegmented, with 1 long terminal plumose seta and 1 slender spine; exopod distally 6-segmented, with 11 marginal plumose setae, 1 distolateral seta and 1 mesial tubercle.

Mandible (Fig. 2 G): Palp absent; incisor and molar processes well differentiated; with lacinia mobilis.

Maxillule (Fig. 2 H): Coxal endite with 7 (2 subterminal+5 terminal) setae; basial endite with 2 strong setae and 3 cuspidate setae; endopod unsegmented, with 2 subterminal setae and 3 terminal setae; exopod absent.

Maxilla (Fig. 2 I): Coxal endite bilobed with 8+3 setae; basial endite bilobed with 4+4 setae; endopod with 9 (3+2+1+1+2) setae; scaphognathite margin with 5 plumose setae.

First maxilliped (Fig. 2 J): Coxa with 4 setae; basis with 10 setae; endopod unsegmented with 3, 1, 2, 4 (1 subterminal+3 terminal) setae; exopod unsegmented with 4 long plumose natatory setae.

Second maxilliped (Fig. 2 K): Coxa with 1 seta; basis with 9 setae; endopod 4-segmented with 3, 1, 2, 5 (1 subterminal+4 terminal) setae; exopod unsegmented with 5 long plumose natatory setae.

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

Pereiopods: Absent.

Abdomen (Fig. 2 A, C): With 5 somites and without setae or spines.

Pleopods: Absent.

Uropods: Absent.

Telson (Fig. 2 A): Subtriangular, posterior border with 7+7 setae, outermost 2 pairs only plumose on inner margin; bases of each seta except outermost one with row of minute spinules.