Archasterope apex Kornicker ex Kornicker & Poore 1996

Archasterope apex Kornicker

ETYMOLOGY.—From the Latin apex (tip, top).

HOLOTYPE.—NMV J37164, ovigerous female on slide and in alcohol.

TYPE LOCALITY.—Slope 47, 41°58.60′S, 148°38.80′E, Tasmania, off Freycinet Peninsula; depth 500 m.

PARATYPES.—None.

DISTRIBUTION.—Slope 47, 500 m.

DESCRIPTION OF ADULT FEMALE (Figures 87–89).—Carapace elongate with slightly convex dorsal and ventral margins and evenly rounded anterior and posterior margins; incisur ventral to midheight (Figure 87a).

Infold: Anterior and anteroventral infold with numerous bristles (Figure 87b); broad list of posterior infold with 22–24 broad transparent bristles with pores at base and with 3–6 long and 42–47 short bristles (Figure 87c); posterior infold between broad list and posterior end of valve with 7 processes and about 40 bristles; about 45 bristles in row on ventral infold between anteroventral infold and ventral end of broad list of posterior infold.

Selvage: Fringed lamellar prolongation along inner part of ventral edge of incisur. Right valve with row of long hairs near dorsal end of broad list of posterior infold (Figure 87c); left valve with row of short spines at that locality.

Vestment: Anterodorsal part of vestment proximal to infold with few rows of long hairs.

Central Adductor Muscle Attachments (Figure 87d): Comprising about 22 ovoid attachments just anterior to valve midlength and just ventral to valve midheight.

Carapace Size (length, height in mm): NMV J37164 (holotype), 2.13, 1.22, height 57% of length.

First Antenna (Figure 87e): 1st joint with medial and lateral spines. 2nd joint spinous, with 2 bristles (dorsal long spinous, lateral short with few indistinct spines). 3rd joint with well-defined distal margin, small ventral bristle, and 6 dorsal bristles (2 single proximal, 2 almost adjacent, 2 paired distal; medial of distal pair with short spines, others with long proximal and short distal spines). 4th joint with slightly concave distal margin, few minute ventral spines, and 3 bristles (1 long dorsal with short spines, 2 short ventral with few indistinct short spines). Sensory bristle of 5th joint with short proximal filament and 6 long terminal filaments. Medial bristle of 6th joint longer than a-bristle of 7th joint, with short marginal spines. 7th joint: a-bristle claw-like with indistinct proximal dorsal spines; b-bristle (not shown) about 1 times length of a-bristle, with 4 marginal filaments, some with spines; c-bristle longer than sensory bristle of 5th joint, with 13 marginal filaments and bifurcate tip. 8th joint: Filament-like d-and e-bristles reaching distal end of sensory bristle of 5th joint, bare with blunt tips; e-bristle slightly stouter than d-bristle but same length; f-bristle bent dorsally, about twice length of a-bristle, with 6 marginal filaments, some with spines; g-bristle (not shown) about same length as c-bristle, with 10 filaments (tip obscured).

Second Antenna: Protopodite with small distal medial bristle, distal spines on dorsal margin, and medial spines on dorsal half (Figure 87f). Endopodite 3-jointed with long terminal filament (Figure 87f). Exopodite: 1st joint with distal spines along dorsal margin; bristle of 2nd joint reaching 9th joint, with numerous slender spines along ventral margin; bristles of joints 3–8 with natatory hairs and proximal ventral spines (spines on bristles of joints 7 and 8 minute); 9th joint with 4 bristles (2 long with natatory hairs, 2 short with short slender spines); joints 4–8 with small basal spines; spine of 8th joint about length of 9th joint; 9th joint with lateral spine about length of joint; joints 2–8 with row of minute spines along distal edge.

Mandible: Coxale endite broken off on both limbs of holotype. Basale endite with 4 spinous end bristles, glandular peg with minute terminal papillae, 2 dwarf bristles, and 4 triaenid bristles (3 shown), each with 8–17 pairs of spines (distal pairs larger) excluding terminal pair. Basale (Figure 88a,b): Ventral margin with triaenid bristle with 4 or 5 pairs of spines excluding terminal pair proximal to deep U-shaped boss; dorsal margin with 7 short bare bristles (proximal 3 medial) and 2 long terminal bristles with short spines. Exopodite hirsute, about length of dorsal margin of 1st endopodial joint, with diaphanous hirsute terminal process and 2 short spinous subterminal bristles (Figure 88b). 1st endopodial joint with 3 long ventral bristles (1 with short spines, 2 with long spines) (bristles not shown). 2nd endopodial joint: Dorsal margin with 4 unequal slender bare proximal bristles, stout spinous a-, b-, c-, and d-bristles (base of c-bristle about same width as base of d-bristle), 1 long spinous lateral e-bristle between b- and c-bristles, 1 long spinous lateral f-bristle between c- and d-bristles, 1 long spinous medial g-bristle near base of d-bristle, and 17 spinous cleaning bristles (5 near bases of a- and b-bristles, 5 between bases of b- and c-bristles, and 7 between bases of c- and d-bristles (outer cleaning bristle about length of c-bristle)); ventral margin with 3 long spinous terminal bristles; medial surface with rows of spines. 3rd endopodial joint with stout dorsal claw with small ventral spines, and 5 bristles (1 medium, 4 long) with short spines.

Maxilla (Figure 88c): Epipodite short with slender hirsute tip. Endite I with 4 bristles (1 short slender, 3 long stout spinous); endite II with 3 long spinous bristles. Basale: Medial surface near dorsal margin with 1 bare proximal bristle, 1 short bare bristle at midlength, and 1 short bare distal bristle; ventral margin with 1 bare proximal bristle, 1 small distal bristle (base on lateral side), and 1 long spinous terminal bristle; lateral side with 1 proximal bristle near midheight; medial surface and dorsal and ventral margins spinous. 1st endopodial joint with small bare alpha-bristle near distal end, and long spinous beta-bristle. 2nd endopodial joint with long spinous terminal bristle slightly shorter than beta-bristle.

Fifth Limb (Figure 88d): Lateral side of comb with stout spinous exopodial bristle reaching past end of comb, 2 short slender bristles just ventral to base of stout bristle, 2 pairs of bristles closer to ventral margin of comb near midlength, and 2 distal bristles almost on ventral margin.

Sixth Limb (Figure 88e): Limb hirsute; posterior end broadly rounded. Small medial bristle near proximal anterior comer. Anterior margin with bristle at upper and lower sutures. Anteroventral comer with 5 small bristles; lateral flap without bristles; posteroventral margin with 19–22 spinous bristles.

Seventh Limb (Figure 89a): Each limb with 12 bristles: 6 proximal (3 on each side, 2 bristles with 3 and 1 with 5 bells) and 6 distal (3 on each side, 2 bristles with 3 and 1 with 5 bells). Terminus with opposing combs, each with 13 or 14 spinous teeth (teeth at each end of comb slightly shorter).

Furca (Figure 89b): Each lamella with 9 claws (posterior claw bristle-like, recurved); claws 1–8 with long and short teeth along posterior edges (not shown); claws 1–5 or 6 with distal hairs along anterior edges (not shown); small triangular process posterior to lamella with minute indistinct spines.

Bellonci Organ (Figure 89c): Elongate, crinkled proximally, broad striate with suture or fold at midlength, then tapering to rounded tip.

Eyes: Medial eye unpigmented, bare (Figure 89c). Lateral eye well developed, about same size as medial eye, unpigmented, with 23 ommatidia (Figure 89c,d) (when body viewed laterally with eye in place small ommatidia along dorsal edge not visible (Figure 87a)).

Genitalia (Figure 89g): Oval structure on each side of body anterior to furca.

Lips: Upper lip a hirsute lobe on each side of indented saddle; a minute anterior spine dorsal to lobe (Figure 89e). Lower lip a hirsute flap on each side of mouth (Figure 89e,f).

Anterior of Body: Without anterior process.

Posterior of Body (Figure 89b): Hirsute dorsal to dorsal end of girdle; with short spinous thumb-like process.

Y-Sclerite (Figure 89b,g): Typical for subfamily.

Eggs: Holotype with 13 eggs in marsupium (1 shown in Figure 87a); lengths of 3 eggs in mm (excluding transparent sheath) 0.33, 0.33, 0.34.

COMPARISONS.—The maxilla of A. apex differs from those of previously described species of the genus in having only 1 proximal ventral bristle on the basale; other species have at least 4. The basale of the mandible of A. efficax differs from that of A. apex in having only 3 instead of 9 dorsal bristles.