Eurypylus matrix Kornicker ex Kornicker & Thomassin 1998

Eurypylus matrix

ETYMOLOGY.—From the Latin matrix (mother, womb, source).

HOLOTYPE.—Ovigerous female on slide and in alcohol.

TYPE LOCALITY.—BT-230.

PARATYPES.—BT-230: 1 juvenile. BT-231: partly dissected juvenile male.

DISTRIBUTION.—BT-230, BT-231; depth 21–24 m.

DESCRIPTION OF ADULT FEMALE (Figures 73–75a–f).—Carapace oval in lateral view with posterodorsal bulge (Figure 73), projecting posteroventral process with rounded tip (Figures 73, 74a), and without incisur or rostrum.

Ornamentation: Carapace with numerous distinct round fossae (Figure 73), many with minute peripheral processes pointing inward (not shown). Outer surface including valve margins with very few bristles.

Infold: Broad infold along anterior and ventral margins, and in caudal area. Anterior infold with small bristle near midheight. Infold of caudal area with 11 or 12 small bristles forming irregular row in anterior part and 1 bristle in posterior part (Figure 74a); 2 setal bristles present on posterior infold dorsal to midheight; inner margin of infold in caudal area with several small bristles.

Carapace Size (length, height in mm): Holotype, 1.82, 1.58.

First Antenna (Figure 74b): 1st joint bare. 2nd joint with spinous dorsal bristle. 3rd joint fused to 4th, with 2 long bristles (1 ventral, 1 dorsal). 4th joint with 4 long bristles (3 ventral, 1 dorsal). Sensory bristle of long 5th joint with minute distal filament and terminal spine. 6th joint fused to 5th, with short spinous medial bristle. 7th joint: a-bristle about 4 times length of bristle of 6th joint; b-bristle almost twice length of a-bristle, with minute distal filament and terminal spine; c-bristle about same length as bristle of 5th joint, with minute distal filament and terminal spine. 8th joint: d- and e-bristles slightly longer than b-bristle, bare with blunt tips; f-bristle slightly longer than d-bristle, with terminal spine; g-bristle shorter than c-bristle, with minute distal filament and terminal spine.

Second Antenna: Protopodite bare (Figure 74c). Endopodite 2-jointed (Figure 74c): 1st joint with 2 small ringed bare anterior bristles and rows of medial spines; 2nd joint small without basal suture, with small unringed terminal spine-like bristle with minute terminal spine. Exopodite: 1st joint with small recurved terminal medial bristle; bristle of 2nd joint with 8–10 stout proximal ventral spines and distal natatory hairs; bristles of joints 3–8 with stout proximal ventral spines and distal natatory hairs; 9th joint with 2 bristles (ventral stout with proximal ventral spines and distal natatory hairs; dorsal short slender with small slender marginal spines).

Mandible (Figure 74d,e): Coxale endite consisting of stout spine. Coxale with spines along ventral margin and on lateral surface near ventral margin. Basale: dorsal margin with 2 minute bristles (1 at length, 1 subterminal); ventral margin with 4 short bristles (3 proximal, 1 distal) with bases on medial side or on margin, and 2 short bristles with bases on lateral side. Exopodite small and weakly developed (Figure 74e). Endopodite: 1st joint: medial surface with distal spines and spines along dorsal half of distal edge; dorsal margin with small terminal spines; 2nd joint with minute terminal spine-like bristle on dorsal margin and stout ventral claw; 3rd joint with stout terminal claw and 1 or 2 small ventral bristles.

Maxilla (Figure 74f,g): Endite I with 6 bristles (3 pectinate, 3 spinous) (Figure 74f); endite II with 4 bristles (2 pectinate); endite III with 6 bristles (2 pectinate (1 unringed), 4 spinous). Coxale with dorsal fringe of hairs and short ringed dorsal bristle (not shown). Basale with 1 bristle near exopodite (not shown). Exopodite with 3 ringed bristles (1 long spinous, 2 shorter bare). Endopodite: 1st joint with slender spinous alpha- and beta-bristles; 2nd joint with 2 spinous a-bristles, 1 spinous c-bristle, and 5 pectinate end bristles.

Fifth Limb (Figure 74h): Epipodial appendage with 43 bristles. Single endite with 1 small bristle. Exopodite: 1st joint with 3 bristles (1 long, 2 shorter); 2nd–5th joints fused, with total of 10 bristles (3 long and 1 minute on 2nd joint; 2 long and 1 minute on inner lobe of fused 3rd joint; 1 small on outer lobe of 3rd joint; 2 long on 4th plus 5th joints).

Sixth Limb (Figure 75a): Single endite with 3 spinous bristles. End joint with 15 ringed bristles (with short spines) forming 2 rows (6 bristles in medial row set back from edge, 9 bristles along edge) followed by space and then posterior projection with 2 stout plumose unringed terminal bristles; dorsal part of posterior projection with long medial hairs. (Rings not shown on all bristles.)

Seventh Limb (Figure 75b): Each limb with 8 or 9 proximal bristles: 4 or 5 short bristles (with 3 or 4 bells) on one side, and 4 longer bristles (with 5 bells) on opposite side. Terminal segment with 6 bristles (with 3–7 bells), 3 on each side, and opposing combs each with 5 or 6 long teeth. Clapper projecting from terminal bell on bristles broadening distally and with rounded tip.

Furca (Figure 75c): Each lamella with 5 claws decreasing in length posteriorly along lamella; claws 1 and 2 nonarticulated, claws 3–5 articulated; all claws with teeth along posterior edge (not shown); few teeth on claws 1 and 2 slightly larger than others; anterior edge of right lamella with few small spines; several small spines on each lamella following last claw; right lamella anterior to left by width of base of claw 1.

Bellonci Organ: Absent on holotype (broken off?) (Figure 75e), but present on juvenile male described below (Figure 75i).

Eyes: Medial eye bare, with 2 amber-colored areas (Figure 75e). Lateral eye distinct, smaller than medial eye, with 5 amber-colored ommatidia (Figure 75d).

Upper Lip (Figure 75f): With anterior projection and short ventral spines; curved sclerite with ventral spines along left side of lip.

Genitalia: Oval sclerotized rim with attached spermatophore on each side of body anterior to furca.

Y-Sclerite: Typical for family.

Eggs: Holotype, with 6 eggs in marsupium and also unextruded eggs; length of 2 extruded eggs 0.23 mm and 0.25 mm (eggs in early stage, containing globules and no appendages); length of unextruded egg 0.14 mm.

DESCRIPTION OF JUVENILE MALE (Figure 75g–i).—Carapace similar to that of adult female except caudal process at posteroventral corner (Figure 75g).

Carapace Size (length, height in mm): Sta BT-231: 1.07 mm, 0.98 mm.

First Antenna: Number of bristles similar to those of adult female except 4th joint with only 2 ventral bristles.

Second Antenna: Protopodite (Figure 75h) and exopodite similar to those of adult female. Endopodite 3-jointed (Figure 75h): 1st joint with 2 small proximal anterior bristles; 2nd joint elongate with short distal bristle; 3rd joint elongate with 2 small terminal bristles.

Mandible, Maxilla, and Fifth Limb: Not examined in detail but of similar type to those of adult female.

Sixth Limb: Not examined in detail but present, and with many bristles.

Seventh Limb: None observed, probably absent.

Furca and Y-Sclerite: Similar to those of adult female.

Bellonci Organ (Figure 75i): Elongate, broadening distally, with rounded tip.

Eyes (Figure 75i): Medial eye bare, unpigmented. Lateral eye unpigmented, about same size as medial eye, with 4 large and several smaller ommatidia.

Upper Lip: Not examined.

Genitalia: None observed, probably absent.

COMPARISONS.—The 7th limb of E. matrix differs from those of previously described species of Sarsiellidae in the unsymmetrical distribution of proximal bristles (short bristles on one side, longer bristles on the other side).

CYLINDROLEBERIDIDAE Müller, 1906

This family includes three subfamilies: Cylindroleberidinae Müller, 1906; Cyclasteropinae Poulsen, 1965; and Asteropteroninae Kornicker, 1981. Representatives of all subfamilies are in the Madagascar collection. The last two families were reported in Kornicker (1981), and for completeness, the species recorded are listed in the station data (see Appendix).

CYLINDROLEBERIDINAE Müller, 1906

This subfamily includes 16 genera of which four have been reported from the western Indian Ocean: Cylindroleberis, Heptonema, Prionotoleberis, and Synasterope (Kornicker, 1992:171). All except Prionotoleberis are in the present collection. In addition, a new species of Parasterope is described herein, and another species of Parasterope is left in open nomenclature.

Synasterope Kornicker, 1975

TYPE SPECIES.—Synasterope implumis Poulsen, 1965, by subsequent designation (Kornicker, 1975:440).

COMPOSITION AND DISTRIBUTION.—The genus comprises about 25 species, including three from the Indian Ocean, and is circumglobal between latitudes of about 47.5°N and 73°S and depths of 1–4450 m (Kornicker, 1992:194). (Kornicker (1992:2) incorrectly stated that Synasterope had been reported from the Arctic Ocean (the genus Vargula had been intended).)