Eurypylus hapax Kornicker & Iliffe 2000

Eurypylus hapax

ETYMOLOGY.—From the Greek hapax (once only).

HOLOTYPE.—USNM 194494, Instar IV female on slide and in alcohol.

TYPE LOCALITY.—Sta 95–002, transect BA, Exuma Sound, Bahamas, depth 142 m.

PARATYPES.—None.

DISTRIBUTION.—Collected only at type locality.

DESCRIPTION OF INSTAR IV FEMALE (Figures 27–29).—Carapace oval in lateral view with slightly projecting rostrum and short broad caudal process with straight posterior edge (Figure 21a–c).

Ornamentation: Surface without either lateral ribs, short spines, or gel-like coating. Posterior edge of caudal process with 7 bristles with bases either on lateral side or along edge (Figure 27a,c,e). Bristles, some with wide proximal part, present along valve edge and scattered on outer surface; all bristles with pointed tips (Figure 27a–e). Outer surface with minute triangular processes (on USNM 194494 processes restricted to edges of valves and best visible on posterior edge of caudal process (Figure 27e)).

Infold: Anterior infold with small bristle dorsal to incisur (Figure 27d). Caudal process with scattered small pointed bristles (Figure 27e). Two setal bristles on infold just dorsal to caudal process.

Selvage: Broad lamellar prolongation with smooth outer edge present along free margins and extending past posterior end of caudal process.

Central Adductor Muscle Attachments: Consisting of numerous small oval attachments (Figure 27f).

Carapace Size (total length, height in mm): USNM 194494, 0.87, 0.70.

First Antenna (Figure 28a,b): 1st joint bare. 2nd joint with dorsal bristle with indistinct spines. 3rd and 4th joints fused; 3rd joint with 1 dorsal bristle and no ventral bristle; 4th joint with ventral spines and 3 bristles (1 dorsal, 2 ventral). 5th joint with long ventral bristle with minute distal marginal spine or filament and terminal spine. 6th joint minute, fused to 5th joint, with short medial bristle. 7th and 8th joints fused. 7th joint: a-bristle about twice length of bristle of 6th joint; b-bristle medial and longer than a-bristle; c-bristle about same length as bristle of 5th joint, with small proximal filament and terminal spine. 8th joint: d-bristle about same length as bristle of 5th joint, bare with blunt tip; e-bristle about length of d-bristle, bare with blunt tip; f-bristle shorter than c-bristle, with minute terminal spine; g-bristle about same length as bristle of 5th joint, with minute indistinct proximal filament and terminal spine.

Second Antenna (Figure 28a–c): Protopodite bare. Endopodite 1-jointed, with medial spines, proximal ringed anterior bristle, and minute spine or bristle adjacent to slight terminal protuberance (Figure 28c). Exopodite: 1st joint with small terminal medial bristle with blunt tip; bristles of joints 1–8 long with slender ventral spines and distal natatory hairs; 9th joint with 2 bristles (dorsal short with few minute spines, ventral long with slender ventral spines and distal natatory hairs).

Mandible (Figure 28a,d,e): Coxale endite consisting of 1 or 2 short stout spines in proximal ventral corner; ventral margin of coxale with hairs, and surface near ventral margin with slender spines. Basale: ventral margin with 4 small medial and 2 small lateral bristles; dorsal margin with 3 small bristles (1 distal to midlength, 2 subterminal). Exopodite absent. 1st endopodial joint with medial, ventral, and dorsal spines, and stout ventral terminal claw with proximal ventral and dorsal spines. 2nd endopodial joint with stout ventral claw and small dorsal bristle. 3rd endopodial joint with stout terminal claw and 2 minute bristles (1 ventral, 1 dorsal).

Maxilla: Endite I with 2 lobes with medial spines, proximal lobe with 1 unringed terminal bristle, distal lobe with 5 bristles (1 ringed, 4 claw-like) (Figure 28f); endite II with 4 bristles (Figure 28f); endite III with 5 bristles (Figure 28g,h). Coxale with short ringed dorsal bristle and long dorsal hairs (Figure 28h). Basale with bristle near exopodite (Figure 28h). Exopodite with 3 bristles (1 long, 2 short). 1st endopodial joint with few distal spines on anterior margin and pectinate alpha-and beta-bristles. 2nd endopodial joint with 2 a-bristles, 1 c-bristle, and 5 pectinate end bristles (middle bristle shortest, anterior longest).

Fifth Limb (Figure 29a): Single endite with short bristle. 1st exopodial joint with 2 spinous bristles; 2nd exopodial joint with 3 spinous terminal bristles; joints 3–5 fused with total of 7 bristles. Exopodial joints 2–5 hirsute.

Sixth Limb (Figure 29b): Single endite with 3 short bristles. End joint with 11 spinous anterior bristles followed by short space and 2 stout hirsute bristles.

Seventh Limb (Figure 29c–e): Limb with 8 tapered bristles, 4 in proximal and 4 in terminal group, each with 2 or 3 bells. Terminus with opposing combs, each comb with about 3 minute teeth.

Furca (Figure 29f): Each lamella with 5 claws decreasing in length along lamella; claws 1 and 2 nonarticulated, claws 3–5 articulated. All claws with teeth along posterior margin; few teeth on claws 1–3 slightly stouter than others; teeth of claw 5 indistinct. Few spines on lamellae following claws. Right lamella anterior to left by width of base of claw 1.

Bellonci Organ (Figure 29g): Elongate, broadening near rounded tip.

Eyes: Medial eye bare with line of brown pigment near midheight (Figure 29g). Lateral eye smaller than medial eye, with 5 divided amber-colored ommatidia (Figures 27a, 28b, 29g).

Upper Lip (Figure 28e): Projecting anteriorly, bare.

Posterior of Body (Figure 29h): With few indistinct spines at posterodorsal corner dorsal to posterior end of girdle.

Genitalia: None observed.

Y-Sclerite (Figure 29h): With ventral branch typical for family.

REMARKS CONCERNING 7TH LIMB.—The holotype, USNM 194494, is an instar IV female and the 7th limb has some juvenile characters. It is likely that the 7th limb of the adult female will have cylindrical rather than tapered bristles, 2 proximal anterior bristles rather than only 1, 6 rather than 4 terminal bristles, and more strongly developed opposing terminal combs.

COMPARISONS.—The absence of secondary claws on the furca of E. hapax places the species in the E. rousei group of Kornicker (1996, table 3). The only known species in that group having five furcal claws on each lamella is E. concentricostatus (Hartmann, 1974). The carapace of E. hapax is without the concentric rib present on E. concentricostatus.

CORRECTION.—Kornicker (1996, table 3) incorrectly listed E. concentricus instead of E. concentricostatus.