Macroasteropteron mindax

Macroasteropteron mindax

ETYMOLOGY.—From the Greek mindax (a Persian incense).

HOLOTYPE.—Adult female with unextruded eggs on slide and in alcohol in the collection of the Museum of Victoria.

TYPE LOCALITY.—Slope 53, 34°52.72′S, 151°15.04′E, New South Wales, 54 km ESE of Nowra; depth 996 m.

PARATYPES.—None.

DISTRIBUTION.—Slope 53, 996 m.

DESCRIPTION OF ADULT FEMALE (Figures 105–108).—Carapace oval in lateral view with small rostrum and shallow incisur (Figure 105). Surface with minute spines and scattered short and long bristles more numerous along margins (Figure 105b,c,e). Dorsal margin anterior to anterior juncture and posterior to posterior juncture with locking structures (Figure 105d–h).

Infold: Infold of rostrum with 2 small divided bristles (Figure 105e,f). Posterior infold with many small undivided bristles (Figure 105g,h). Crenulations visible beneath anterorventral and ventral infolds viewed from inside (Figure 105e) (crenulations more irregular along posterior half of ventral margin). Vestment of posterodorsal corner of right valve with long spines (Figure 105h).

Selvage: Continuous narrowly striate lamellar prolongation with smooth outer edge extending from dorsal end of anterior margin of rostrum to midheight of posterior margin of valve at locking structures; prolongation narrower along posterior margin.

Central Adductor Muscle Attachments (Figure 105a,d): About 20 ovoid attachments.

Carapace Size (length, height in mm): Holotype, 1.42, 1.02.

First Antenna (Figures 106a–c, 108g): Joints 1–7 spinous; 2nd joint short, separated from 3rd joint by indistinct suture; 3rd joint long with 2 bristles (1 ventral terminal, 1 dorsal at distal ); 4th joint long with 3 terminal bristles (1 dorsal, 2 ventral). Sensory bristle of 5th joint with 2 small bare proximal filaments, then 2 long filaments each with 2 terminal spines, then bifurcating into 2 filaments (each about half length of long filaments) each with 2 spines at tip. 6th joint fused to 5th, with small medial bristle. 7th joint: a-bristle ringed, not claw-like, with long proximal and shorter distal spines; b-bristle short, about same length as bristle of 6th joint, with stout proximal part (possibly stump of incompletely shed bristle of previous instar); c-bristle about same length as sensory bristle of 5th joint, with 4 bare proximal filaments and bifurcate tip. 8th joint: d-bristle absent; e-bristle about half length of c-bristle, bare with blunt tip; f-bristle slightly longer than e-bristle, with 3 bare proximal filaments and bifurcate tip; g-bristle slightly shorter than c-bristle, with 4 bare proximal filaments and bifurcate tip.

Second Antenna (Figure 106d,e): Protopodite spinous, with small distomedial bristle. Endopodite 3-jointed: 1st joint short, with medial spines and 4 small ringed bristles (bare or with few indistinct spines); 2nd joint short spinous, with no or 1 small ringed bristle; 3rd joint spinous, elongate, triangular, with small indistinct proximal tooth and minute cylindrical terminal process. Exopodite: 1st joint with small, slightly curved, tubular, medial, terminal bristle; bristles of joints 2–8 with natatory hairs, no spines; 9th joint with 3 bristles (2 long with natatory hairs, 1 short bare (dorsal)); basal spines absent; joints 2–8 with minute indistinct spines along distal edges.

Mandible: Coxale endite: ventral branch with 4–6 rows of spines and tip with stout dorsal tooth and 2 pairs of smaller teeth (Figure 106e,f); dorsal branch with 6 small pointed distal ventral processes including main spine; tip indistinct, rounded, right limb of holotype with terminal hairs (Figure 106f), left limb with terminal spines (could not resolve with certainty whether spine at midheight stouter than others) (Figure 106g); usual terminal dorsal bristle not observed; small slender ringed medial bristle present near base of ventral branch (Figure 106f). Basale endite with 8 stout spinous bristles and 1 indistinct dwarf bristle (Figure 106b). Basale (Figure 106h): ventral margin with 4 ringed triaenid bristles and 2 longer slender terminal ringed bristles (bases of latter on small lobe beneath terminal medial edge of joint on illustrated limb) with indistinct short spines; dorsal margin with 2 long bare subterminal ringed bristles; medial surface spinous (spines long near dorsal margin, shorter and stouter at midheight (not all spines shown)); lateral side with spines near dorsal margin. Exopodite about same length as dorsal margin of 1st endopodial joint, hirsute distally, with rounded tip and 2 small ringed terminal bristles. 1st endopodial joint with few rows of medial spines and 2 long ventral ringed bristles with long proximal and short distal spines (only proximal ends of bristles shown). 2nd endopodial joint (Figure 106h): ventral margin with 2 long terminal ringed bristles with short spines; dorsal margin with 3 short or medium proximal ringed bristles, 2 long distal ringed bristles, 1 very small ringed bristle lateral to distal long bristle, and 4 short spinous unringed cleaning bristles medial to proximal long bristle; medial surface of joint with rows of spines. 3rd exopodial joint with 4 ringed bristles (2 long stout claw-like bristles ringed (rings incomplete) except at talon-like tips and with indistinct small ventral spines, 1 ringed bristle somewhat claw-like about half length of longest bristle, and 1 small ringed medial bristle with small spines) (Figure 106i). (Rings not shown on all bristles.)

Maxilla: Epipodite short, hirsute, diaphanous, with pointed tip (Figure 107d). Endite I with 3 long bristles with spines at tip and 1 minute indistinct medial bristle (Figure 107a,b); endite II with 4 long bristles (anterior bristle of left limb shown in Figure 107c; 3 posterior bristles shown in Figure 107a). Baleen comb extends laterally past 1st endopodial joint (anterior end of comb at anterior distal corner of basale) (anterior 2 bristles of comb shown in Figure 107d) (proximal bristle of comb shown in Figure 107a,b). Basale (Figure 107c,d): lateral side with long slender bristle at midlength and midheight; dorsal margin with no or 1 proximal bristle, 1 distal bristle, and 1 long spinous terminal bristle (this bristle usually adjacent to posterior edge of 1st endopodial joint in other Asteropteroninae); medial surface with spines in ventral half. Exopodite absent. 1st endopodial joint medial to anterior end of basale, spinous, with short alpha-bristle on posterior side and long terminal beta-bristle on anterior side (reverse of usual location of these bristles). 2nd endopodial joint with 1 long and 2 short bare bristles. (The 1st endopodial joint appears to be reversed, with the margin anterior in other members of the family, posterior on this specimen. Although possible, the 2 limbs mounted on the slide do not appear to have been mechanically twisted during the mounting process suggesting that the reversal is either an aberrancy or a generic character.) (Right limb of holotype without alpha-bristle, but empty socket visible on 1st endopodial joint, and a loose bristle present not far from socket is about same length as alpha-bristle on left limb. The bristle is shown dashed in Figure 107d.)

Fifth Limb (Figure 107e,f): Comb with single row of 26 spinous ventral ringed bristles (only 2 proximal and 2 distal bristles shown on illustrated left limb (Figure 107e), and 1 distal bristle on illustrated right limb (Figure 107f)) and 1 small distal lateral bristle near dorsal margin; proximal medial bristles (rings not shown) on illustrated limbs are interpreted not to be on comb. (Rings are shown on only ventral bristles.)

Sixth Limb (Figure 107g,h): Limb hirsute. Anterior margin of trunk with about 13 spinous medial ringed bristles. Skirt short with rounded anterior and posterior ends, with about 31 spinous ringed bristles on medial surface and along edge (Figure 107g; medial bristles not shown on Figure 107h). (Rings and not all spines shown on bristles.) (Shape of end joint unusual for subfamily.)

Seventh Limb (Figures 107i,j, 108d): One limb with 7 (3 + 4) proximal bristles, other with 9 (5 + 4); each bristle with 3–5 bells. Terminus with large bilobed process surrounded by 16 or 17 spinous teeth (8 or 9 on each lobe); 2 internal muscles attached at distal third (Figure 107j).

Furca (Figure 108d): Each lamella with 8 claws (3 stout claws followed by 5 shorter slender claws) followed by 3–5 short spinous processes, then groups of minute spines; small spines on lamella just posterior to each claw; all claws with closely spaced slender teeth along posterior edge (not shown); claws 1–3 with thin spines along anterior edge (not shown); anterior edge of lamella with spines.

Bellonci Organ (Figures 107k, 108a): Elongate, slightly broader in distal third, with rounded tip.

Eyes: Lateral eyes absent. Medial eye small, unpigmented (Figure 107k).

Lips (Figure 108a–c): Upper lip 2 hirsute lobes without anterior spines; elongate process at body midwidth just dorsal to lobes with vertical row of minute spines. Lower lip a hirsute flap at each side of mouth and posterior to each lobe of upper lip.

Genitalia (Figure 108d): Oval on each side of body anterior to furca.

Anterior of Body (Figure 108a–c): With large hirsute bulge between medial eye and upper lip dorsal to spiny ridges. Small lateral process at each side of body near dorsal end of upper lip (Figure 108c).

Posterior of Body (Figure 108d–f): Posterior spinous with spinous finger-like dorsal process.

Y-Sclerite (Figure 108d): Anterior end not protracted (somewhat obscured).

Gills (Figure 108d–f): Three indistinct diaphanous gills on each side of dorsal margin of body anterior to finger-like dorsal process.

Number of Eggs: Holotype with 8 large unextruded eggs (4 on each side) of similar size (2 eggs shown in Figure 108d); length of 1 egg, 0.2 mm.