Heptonema latum Kornicker 1986

Heptonema latum

Heptonema latum Kornicker in Bowen et al., 1979, fig. 3 [deliberate nomen nudum].

ETYMOLOGY.—The specific name is from the Latin latus (“broad, wide”), in reference to the broad posterior end of the 6th limb of this species.

HOLOTYPE.—USNM 156943, 1 ovigerous female in alcohol and on slides.

TYPE-LOCALITY.—Continental shelf, New Jersey, R/V Columbus Iselin station F2, 12 Nov 1975, 38°44′14″N, 73°09′08″W, 110–112 m.

ALLOTYPE.—USNM 156799, 1 adult male in alcohol and on slides, from Beaufort Shelf Transect station 61Q, North Carolina.

PARATYPES.—USNM 157697, 1 ovigerous female from R/V Columbus Iselin station F4, 7 Nov 1975; USNM 157830, 1 ovigerous female from R/V Columbus Iselin station A3, 11 Nov 1975; USNM 157829, 1 juvenile male, from R/V Columbus Iselin station F4, 10 Nov 1975; USNM 156942, 1 A-2? male, from R/V Columbus Iselin station A4, 11 Nov 1975; 2 specimens from Gulf of Maine.

DISTRIBUTION.—New Jersey, North Carolina, Maine continental shelf and upper slope at depths of 110–239 m.

DESCRIPTION OF ADULT FEMALE (Figures 21–22f).—Carapace elongate with short incisur below valve middle (Figure 21a,b); valve highest just posterior to valve middle; in lateral view, posterior less broadly rounded than anterior end; surface smooth.

Infold: Infold behind rostrum with 4 or 5 bristles along distal part of list, about 12 bristles forming row between list and incisur, and about 85 bristles anterior and dorsal to list; about 60 bristles on broad anteroventral infold; about 28 bristles along ventral infold to point opposite lowermost hyaline flap-like bristle on posterior list. List beginning at inner margin of anterior part of infold near incisur, extending along ventral infold and continuing on posterior infold where it broadens; posterior list with about 22 broad transparent flap-like bristles and 22 small bristles (generally 1, and not more than 2, small bristles between each pair of flap-like bristles); the small bristles slightly anterior to flap-like bristles; a field of tubular pores present at bases of flap-like bristles; about 8 bristles and 6 processes present between posterior list and posterior valve margin (Figure 21c,d).

Size: USNM 156943, length 1.66 mm, height 1.03 mm; USNM 157697 (distorted valve), length only, about 1.63 mm; USNM 157830, length 1.62 mm, height 1.10 mm.

First Antenna (Figure 21e,f): 1st joint spinous. 2nd joint spinous, with 1 long, spinous, dorsal bristle and 1 short, spinous, lateral bristle. 3rd and 4th joints fused, very short; 3rd joint with minute ventral bristle and 6 long, spinous, dorsal bristles. 4th joint with strongly concave distal margin, spines and 2 short bristles on ventral margin, and 1 long spinous bristle on dorsal margin. Sensory bristle of long 5th joint with 7 long terminal filaments. 6th joint with long medial bristle with faint marginal spines. 7th joint: a-claw with faint serrations along dorsal margin; b-bristle about longer than a-claw, with 2 short proximal and 3 long terminal filaments including stem; c-bristle long, with about 8 short marginal filaments. 8th joint: d-bristle missing; e-bristle slightly longer than a-claw, with blunt tip; f-bristle bent dorsally, about same length as b-bristle, with 4 or 5 marginal filaments; g-bristle longer than b-bristle, with about 5 short marginal filaments.

Second Antenna: Protopodite with short, bare, medial bristle, long spines on dorsal half of medial surface and along dorsal margin, and shorter spines on ventral part of medial surface. Endopodite 3-jointed (Figure 21g): 1st and 2nd joints short, bare; 3rd joint short with long terminal bristle with blunt tip. Exopodite 9-jointed: 1st joint elongate with long hairs forming rows along inner dorsal margin and terminal ventral margin; bristle of 2nd joint reaching 8th joint, with abundant long hair-like spines along ventral margin; 3rd joint about length of 2nd; bristles of joints 3–6 with slender, proximal, ventral spines and distal natatory hairs; bristles of joints 7 and 8 with natatory hairs; 9th joint with 3 bristles (1 long and 1 medium with natatory hairs, 1 short with short marginal spines); joints 2–9 with spines forming row along distal lateral margin; joints 2–6 with spines along distal medial margin; no basal spines.

Mandible (Figure 22a): Coxale endite broken off (see description of endite of adult male). Basale: endite with 4 pectinate end bristles, 2 ventral triaenid bristles (with 9 or 10 paired spines excluding terminal pair), 2 dwarf bristles, and small glandular peg; ventral margin bare; dorsal margin with 1 long spinous midbristle and 2 long, spinous, terminal bristles. Exopodite about length of dorsal margin of 1st endopodial joint, hirsute, with 2 short terminal bristles. 1st endopodial joint with 3 long, spinous, ventral bristles. 2nd endopodial joint: dorsal margin with 1 short proximal bristle and stout spinous a-, b-, c- and d-bristles (c-bristle slightly stouter than others); lateral surface with long spinous bristle between b- and c-bristles, and also between d- and e-bristles; medial surface spinous, with 3 cleaning bristles forming row between b- and c-bristles, 7 cleaning bristles forming oblique row with longest bristle near base of b-bristle, and 1 long spinous bristle with base just distal to d-bristle; ventral margin with 3 long terminal bristles (only 1 shown in illustrated limb) 3rd endopodial joint with straight dorsal claw with ventral spines, and 5 bristles (1 short, others long).

Maxilla (Figure 21h): 2 endites present: endite I with 4 bristles (1 short, 3 long); endite II with 3 long bristles. Basale: medial side hirsute, with 1 proximal bristle near dorsal margin; dorsal margin hirsute (hairs not shown in illustrated limb), and with 1 long distal bristle; ventral margin with 1 short midbristle, 1 minute distal bristle, and 1 long, spinous, terminal bristle; lateral side with 1 short proximal bristle near middle. Endopodite: 1st joint with short anterior bristle and long spinous beta-bristle; 2nd joint with 1 long, spinous, terminal bristle extending well past beta-bristle. Epipodial appendage fairly short, triangular, hirsute.

Fifth Limb (Figure 22b): Comb with stout, spinous, exopodial bristle reaching past end of comb, 1 small slender bristle just ventral to base of stout bristle, and 4 short bristles close to ventral margin; additional 4 bristles present on lateral side almost on ventral margin (2 proximal, and 2 near distal corner); anterior margin of comb with long hairs.

Sixth Limb (Figure 21i): Minute medial bristle present just posterior to proximal anterior corner; anterior margin with upper and lower endites indicated by minute suture; upper suture with very small medial bristle; lower endite without bristle. Lateral flap hirsute but without bristles; anterior corner of end joint with 2 or 3 small bristles; posterior end of limb extremely broad; limb hirsute.

Seventh Limb: Each limb with 6 distal bristles (3 on each side) and 4 proximal bristles (3 on one side, 1 on other); bristles with 2–4 bells. Terminus consisting of 2 opposing combs, each with about 15 spinous teeth.

Furca: Each lamella with 9 or 10 pectinate claws (7 strong claws followed by 2 or 3 weaker bristle-like claws); posterior 2 or 3 claws bent backwards.

Bellonci Organ (Figure 22c): Elongate, widening near middle, with rounded tip.

Eyes: Medial eye unpigmented, with short hairs along dorsal margin (Figure 22c). Lateral eyes smaller than medial eye, pigmented brown, each with 3 or 4 faint ommatidia (Figure 22d).

Upper Lip (Figure 22c): Consisting of 2 lobes with medial saddle; lobes and saddle hirsute and with 1 or 2 minute anterior spines. A hirsute lateral flap (lower lip) present on each side of mouth.

Posterior of Body: Small, spinous, thumb-like, posterior process (Figure 22e).

Y-Sclerite (Figure 22f): Unbranched, typical for subfamily.

Gill-like Structures: Well developed.

Eggs: USNM 156943 with 11 eggs in marsupium; USNM 157830 with 6 eggs.

DESCRIPTION OF ADULT MALE (Figures 23, 24).—Carapace unusual in having anterior margin of rostrum somewhat compressed, flaring out in vicinity of incisur (Figure 23a); valve highest just anterior to central adductor muscle attachments, and then becoming narrow posteriorly in series of 2 steps, the 1st step being just dorsal to muscle attachments, and the 2nd step being just anterior to vertical row of bristles near posterior end of valve.

Infold: Anterior infold not examined in detail but, in general, similar to that of adult female; list of posterior infold with about 20 flap-like bristles and 1 small bristle between each pair of flap-like bristles; 4 processes and 2 or 3 bristles present between posterior list and posterior end of valve.

Size: USNM 157799, length 2.02 mm, height 1.00 mm.

First Antenna (Figure 23b,c): 1st joint bare. 2nd joint with 2 spinous bristles (1 dorsal, 1 lateral). 3rd joint short, triangular, with 1 minute ventral bristle and 7 spinous dorsal bristles. 4th joint short with 2 short ventral bristles and 1 long dorsal bristle. 5th joint minute, with stout sensory bristle with abundant filaments (filaments not shown in illustrated limb). 6th joint long with long medial bristle near dorsal margin. 7th joint: a-claw on short pedestal, claw short with faint dorsal marginal spines; b-bristle with missing tip on both limbs of specimen examined, with 4 marginal filaments on remaining part; c-bristle extremely long, with about 25 short marginal filaments along dorsal margin. 8th joint: d-bristle minute, bare; e-bristle about twice length of a-claw, bare with blunt tip; f-bristle extremely long, with about 25 short marginal filaments along ventral margin; g-bristle about twice length of b-bristle, with about 10 short dorsal filaments.

Second Antenna (Figure 23d,e): Protopodite with small medial bristle. Endopodite 3-jointed: 1st joint elongate, bare; 2nd joint elongate with 3 short bristles near middle and 1 long subterminal bristle; 3rd joint reflexed on 2nd, with tapered tip. Exopodite: elongate 1st joint with long hairs along distal margin; 2nd joint elongate, about same length as joints 3–6 combined, with long hairs on distal dorsal corner; joints 3–8 short, with long hairs on distal dorsal corner; joints 2–8 with short spines along distal margins; short 9th joint with 3 bristles (2 long, 1 short; all with natatory hairs); bristles of joints 2–8 with natatory hairs, no spines; basal spines absent.

Mandible (Figure 24a): Coxale endite: small bristle present at base of ventral branch; ventral branch with spines forming 4 or 5 oblique rows, and with slender tip with hair-like spines; ventral margin of dorsal branch with 7 small processes proximal to small main spine; terminal bristle hirsute (placement of base of bristle not clear on mounted limbs); dorsal margin of dorsal branch serrate. Basale: endite with 4 short end bristles, 2 weakly developed triaenid bristles, 2 dwarf bristles, and small glandular peg; dorsal margin of basale with 1 long midbristle, and 2 long terminal bristles (medial of these with stout base). Exopodite hirsute, reaching middle of dorsal margin of 1st endopodial joint, with 2 short bristles. 1st endopodial joint with 3 spinous ventral bristles. 2nd endopodial joint: ventral margin with 3 spinous terminal bristles (spines not shown in illustrated limb); dorsal margin with 3 short proximal bristles and stout spinous a-, b-, c-, and d-bristles; medial surface spinous, with 9 cleaning bristles forming 2 rows (3 in proximal row, 6 in distal row) and 1 bristle near d-bristle; lateral side with 1 long bristle between b- and c-bristles and between c- and d-bristles. End joint with pectinate dorsal claw, 1 short spinous bristle, and 4 long stout bristles.

Maxilla (Figure 24c,b): Similar to that of adult female.

Fifth Limb: Not examined in detail, but, in general, similar to that of adult female.

Sixth Limb (Figure 24d,e): Same shape and with similar distribution of bristles as on adult female.

Seventh Limb (Figure 23f): Similar to that of adult female.

Furca (Figure 24i): Each lamella with 8 claws decreasing in length posteriorly along lamella; last 1 or 2 pairs of claws weak; groups of small teeth alternate with longer teeth along posterior margins of claws; claws decreasing in curvature posteriorly, with claws 4–8 fairly straight.

Bellonci Organ (Figure 24f): Similar to that of adult female.

Eyes: Medial eye light amber, bare (Figure 24f). Lateral eye about same size as medial eye, with amber central part bearing 4 clear marginal lobes, each with 1 or 2 minute amber ?ommatidia. (Figure 24g).

Upper Lip (Figure 24h): Similar to that of upper lip of adult female but anterior spines not observed.

Copulatory Organ (Figure 24i): Paired copulatory limbs small, each consisting of several lobes.

Posterior of Body (Figure 24i): Undulate posterodorsal corner with spines, but thumb-like process as on adult female not observed.

Y-Sclerite (Figure 24i): Similar to that of adult female.

DESCRIPTION OF JUVENILE MALE (A-2? instar) (Figure 22g-l).—Carapace elongate with dorsal margin considerably more convex than ventral margin. (Figure 22g).

Size: USNM 156942, length 1.12 mm, height 0.63 mm.

First Antenna: 1st joint spinous. 2nd joint spinous, with 1 dorsal and 1 lateral bristle; 3rd and 4th joints very short; 3rd joint with 4 long dorsal bristles and 1 minute ventral bristle; distal margin of 4th joint concave, with 1 long dorsal bristle. Sensory bristle of long 5th joint with 6 terminal filaments. 6th joint with long medial bristle. 7th joint: a-claw with minute teeth along dorsal margin, remaining bristles, in general, similar to those of adult female. 8th joint: d-bristle minute; e-bristle almost reaching tip of sensory bristle of 5th joint; f-bristle bent dorsally, with 5 short filaments; g-bristle, in general, similar to that of adult female.

Second Antenna: Prodopodite with long spines along dorsal margin and on dorsal half of medial surface, and with 1 short medial bristle. Endopodite 3-jointed (Figure 22h): 1st joint short bare; 2nd joint bare, longer than 1st joint; 3rd joint about same size as 1st joint, with long bristle near middle. Exopodite: 9th joint with 3 bristles (1 long, 2 short); remaining joints similar to those of adult female.

Mandible: Central branch of coxale endite similar to that of adult male (dorsal branch broken off on specimen examined). Exopodite about length of dorsal margin of 1st endopodite joint, hirsute with 2 small bristles. 2nd endopodial joint with 5 cleaning bristles (1 in proximal row, 4 in distal row); c-bristle wider at base than b- and d-bristles; a-bristle narrower than b-bristle. Remaining limb similar to that of adult male and female.

Maxilla (Figure 22i): Similar to that of adult female except with longer distal bristle on dorsal margin of basale.

Fifth Limb: Not examined in detail but, in general, similar to that of adult female.

Sixth Limb: Similar to that of adult female.

Seventh Limb: 4 proximal bristles (3 on one side, 1 on other); 4 distal bristles (2 on each side); bristles strongly tapering, each with 1 bell; terminus consisting of opposing combs.

Furca: Each lamella with 6 claws; posterior claw bristle-like, bending backwards.

Bellonci Organ (Figure 22j): Elongate, with medial suture and rounded tip.

Eyes: Medial eye bare, lightly pigmented. Lateral eyes minute, unpigmented, each with about 5 faint ommatidia.

Upper Lip: Similar to that of adult female (anterior spines not shown on illustrated lip).

Posterior of Body (Figure 22l): With small, spinous, thumb-like, dorsal process.

DEVELOPMENT.—The A-2? male described herein bears only 6 terminal filaments on the sensory bristle of the 5th joint of the 1st antenna, not 7 as on the adult female. The 7th limb bears 4 proximal bristles on the 7th limb as on the adult female and adult male (3 on one side, 1 on other), but the bristles are strongly tapered and each have only 1 bell. The furcal lamellae have fewer claws than on adults.

COMPARISONS.—The new species, H. latum, differs from the 2 previously described species in the genus in having 4 proximal bristles (3 on one side, 1 on other) rather than 6 (3 on each side) on the 7th limbs, in having poorly developed lateral eyes, and in other characters. It differs from the only other species of the genus known in the study area, H. serratum, in having 6 instead of 4 bristles on the dorsal margin of the 3rd joint of the 1st antenna, and in being larger (carapace length of adult female 1.62–1.66 mm compared to 1.11–1.14 mm).

Bathyleberis Kornicker, 1975

TYPE-SPECIES.—Bathyleberis grossmani Kornicker, 1975:538.

DISTRIBUTION.—Members of this genus have been reported from the Antarctic Ocean, southern Atlantic and Pacific Oceans, and in the vicinity of New Zealand by Kornicker (1975:539). Baker (1979:287) reported 3 new species of Bathyleberis from the continental shelf off southern California. Hiruta (1979:99) described a new species from the Japan Sea off Hokkaido. Chavtur (1978:154, 1983:81) described a new species from the Kurile Islands and polar waters. A new species described herein is from the Gulf of Mexico off Texas. Known depth range of the genus is intertidal to 4303 m.

COMPOSITION.—The genus is represented in the study area by a new species, B. toxotes.