Metavargula quintuplex Kornicker 1989

Metavargula quintuplex

Metavargula species A.—Komicker 1985:410–412 [part, excluding specimens from samples DS-14 (2 specimens) and DS-36 (4 specimens) referred to Metavargula bilix; samples DS-48 and DS-77 referred to Metavargula hex; samples DS-14 (2 juveniles) and DS-76 (1 juvenile, USNM 193263) referred to Metavargula species indeterminate].

ETYMOLOGY.—From the Latin quintuplex (fivefold), in reference to the 5 pectinate teeth of the 1st exopodial joint of the 5th limb of the species.

HOLOTYPE.—Partly dissected ovigerous female in alcohol, MNHN Os 90, Muséum National d'Histoire Naturelle, Paris, France.

TYPE LOCALITY.—BIOGAS II, R.V. Jean Charcot, west of Bay of Biscay, 47°32′12″N, 8°05′18″W, 2138 m, Sanders dredge, sta 1, sample DS-32, 19 Apr 1973.

PARATYPES.—BIOGAS I, R.V. La Perle, sta 1: sample DS-05, 2 females (USNM 193166) + 26 specimens; sample DS-06, 11 specimens; sample DS-07, 1 adult male + 9 specimens; sample DS-09, 125 specimens; sample DS-11, 5 specimens; sample DS-12, 1 ovigerous female; sample DS-13, 10 specimens. POLYGAS, R.V. Jean Charcot, sta 1: sample DS-15, 129 specimens (USNM 193266); sample DS-17, 18 specimens (USNM 193273). Sta 6: sample DS-25, 1 early instar (USNM 193271); sample DS-26, 40 specimens (USNM 193269). BIOGAS II, R.V. Jean Charcot, sta 1: sample DS-32, 25 specimens. Sta 2: sample DS-31, 1 adult male. Sta Hors-Zone: sample DS-33, 9 specimens. BIOGAS III, R.V. Jean Charcot, sta 1: sample DS-35, 1 adult male (USNM 193165) + 8 specimens; sample DS-37, 35 specimens. Sta 2: sample DS-41, 6 specimens. Sta 6: sample DS-49, 8 specimens; sample DS-50, 62 specimens. BIOGAS IV, R. V. Jean Charcot, sta 1: sample DS-61, 4 juveniles; sample DS-62, 39 specimens; sample DS-63, 84 specimens; sample DS-64, 21 specimens; sample CP-01, 1 specimen. Sta 2: sample DS-60, 2 females. Sta 6: sample DS-52, 168 specimens. BIOGAS VI, R.V. Jean Charcot, sta 1: sample DS-71, 40 specimens; sample CP-08, 3 specimens; sample CP-08a, 5 specimens; samples CP-09, 3 specimens; sample CP-09a, 5 specimens. Sta 2: samples DS-73, 1 juvenile; sample DS-75, 1 female. Sta 6: sample DS-87, 111 specimens; sample DS-88, 1 specimen; sample CP-23a, 106 specimens; sample CP-24, 2 specimens; sample CP-24a, 36 specimens; sample Nasca-05, 1 adult male (USNM 158592A) + 82 specimens (USNM 158592B). BIOGAS VIII, R.V. Noroit, sta 1: sample KG-148, 3 early instars; sample KG-158, 1 specimen. BIOGAS IX, R.V. Capricorne, sta 1: sample CP-34, 1 female (USNM 157975) + 11 specimens. BIOGAS XI, R.V. Jean Charcot, sta 3: sample CP-37, 7 specimens. BIOCYAN, sta 1: sample PL-18, 1 juvenile (USNM 193276); sample PL-22, 1 specimen (USNM 193277).

DISTRIBUTION.—In and west of the Bay of Biscay, 1845–3742 m.

CORRECTION.—Kornicker (1985:411) listed a station containing only M. species A (= M. quintuplex) as NA-05(3) from a depth of 4160 m. This station should be Nasca-05 from a depth of 1980 m.

DESCRIPTION OF ADULT FEMALE (Figures 12–14).—Carapace elongate with projecting caudal process below midheight (Figures 12, 13c,d); shell overlapping valve edge along anterior, anteroventral, and ventral margins (Figure 13a–c).

Infold (Figure 13a–c): Rostral infold with 2 bristles (1 long, 1 shorter) at inner end of incisur, 1 fairly long bristle near center of rostrum, and about 16–19 shorter bristle, mostly forming row paralleling outer edge of rostrum; anteroventral and ventral infold with 1 small bristle near inner margin just below incisur, followed by space and then 24–30 short bristles along narrow list; list extending from below incisur to caudal process; list broad anterior to caudal process, with about 10 minute bristles and 30–36 minute processes along posterior edge (Figure 13c); 2 or 3 minute bristles and about 5 distinct pores located on caudal process posterior to list.

Selvage: Lamellar prolongation of selvage broad and indistinctly striate along lower margin of incisur (Figure 13b), narrow along anteroventral and ventral margin of valves as well as along anterior margin of rostrum and dorsal to caudal process; selvage absent at posterior end of caudal process and along upper edge of incisur; lamellar prolongation divided at innermost end of incisur; minute length of prolongation present at innermost end of incisur extending to pair of bristles on rostrum just dorsal to inner end of incisur.

Size: Holotype, length 3.08 mm, height 1.81 mm. Paratypes: USNM 157975, length 2.89 mm, height 1.66 mm; USNM 193166, 2 specimens, length 2.74 mm, height 1.67 mm, length 3.04 mm, height 1.87 mm; BIOGAS I, DS-12, length 2.97 mm, height 1.86 mm; BIOGAS III, DS-41, length 2.98 mm, height 1.74 mm; BIOGAS VI, DS-71, length 3.14 mm, height 1.92 mm; BIOGAS III, DS-41, length 3.19 mm, height 1.81 mm; BIOGAS VI, CP-23a (2 specimens), length 2.91 mm, height 1.73 mm, length 3.00 mm, height 1.81 mm; BIOGAS IV, DS-60, length 3.22 mm, height 1.88 mm.

First Antenna (Figure 13e): 1st joint bare. 2nd joint with marginal spines. 3rd joint with 2 bristles (1 ventral, 1 dorsal). 4th joint with 2 bristles (1 ventral, 1 dorsal). Sensory bristle of 5th joint with 8 long proximal filaments (short proximal part of filaments slightly narrower than distal part) followed by 2 shorter more slender distal filaments (with minute spine at tips) and bifurcate tip. Medial bristle of 6th joint about same length as joint. 7th joint: a-bristle about same length but broader than bristle of 6th joint, with short marginal spines; b-bristle almost twice length of a-bristle, with 4 marginal filaments, some filaments with marginal spines; c-bristle longer than sensory bristle of 5th joint, with 8 marginal filaments and bifurcate tip, some filaments with marginal spines. 8th joint: d- and e-bristles about longer than b-bristle, bare with blunt tips; f-bristle about same length as sensory bristle of 5th joint, with about 10 marginal filaments and bifurcate tip, some filaments with marginal spines; g-bristle about same length as c-bristle, with about 10 marginal filaments and bifurcate tip, some filaments with marginal spines.

Second Antenna (Figure 13f): Protopodite with short medial bristle. Endopodite 2 jointed: 1st joint with 4 bristles (2 short, 1 medium, 1 long), longest with short marginal spines; 2nd joint short, with long terminal bristle. Exopodite: 1st joint with few small spines along dorsal concave margin; joints 3–8 with basal spines increasing in length distally; basal spine of 8th joint about same length as 9th joint; 9th joint with lateral spine same length as joint; bristle of 2nd joint reaching 8th or 9th joint, with about 15 ventral spines, no hairs, distal spine longer than others; bristles of joints 3–8 with natatory hairs, no spines; 9th joint with 4 bristles (3 long, 1 short), all with natatory hairs, no spines.

Mandible (Figure 13 g,h): Coxale endite spinous, with 2 stout spines and medial peg at tip, and with small bristle near base. Basale: ventral margin with 2 short a-bristles, one short b-bristle, 2 c-bristles (1 long with wreaths of long hairs, 1 short bare; short bristle close to and usually proximal to long bristle), and 2 d-bristles (short slender bristle followed by long spinous bristle); dorsal margin with 3 bristles (1 distal to middle, 2 terminal). Exopodite reaching just past distal end of 1st endopodial joint, hirsute distally, with 2 bristles on inner margin (distal of these reaching past midlength of other). 1st endopodial joint with 4 ventral bristles (1 long, 1 medium, 1 short, 1 minute). 2nd endopodial joint: dorsal margin with about 12 bristles (4 of these much longer than others); ventral margin with bristles forming 3 distal groups of 1, 1, and 2 bristles (medial of distal pair stouter than other and with spines on dorsal margin). End joint with 3 claws about same length and 4 ringed bristles (inner of these about same length as claws and slightly broader in its proximal ).

Maxilla (Figure 13i): Protopodite with plumose dorsal bristle. Endite I with 11 spinous bristles; endite II with 5 spinous bristles; endite III with 5 spinous bristles. Basale with small bare bristle at inner distal edge. 1st endopodial joint with 2 alpha-bristles (outer of these long, hirsute; other slender, bare), and 3 beta-bristles (outer and middle bristle pectinate, inner small bristle bare); cutting tooth comprising 2 stout teeth. End joint: 4 a-bristles (shortest bare, others with slender marginal spines), 3 b-bristles, 3 pectinate c-bristles, and 3 d-bristles. Exopodite with 1 hirsute proximal bristle just distal to midlength and 2 terminal bristles of equal length (bristle nearest to proximal bristle hirsute, other bare).

Fifth Limb (Figure 14a–c): Protopodite with short, undulate, anterior, tooth-like process. Endite I with 7 spinous bristles; endite II with 5 bristles (1 short bare, others spinous); endite III with about 6 bristles. Exopodite: anterior side of 1st joint with 1 hirsute bristle near tooth of protopodite, and 2 stouter distal bristles (with proximal wreaths of long spines) closer to main tooth; main tooth comprising smooth triangular tooth followed by 5 pectinate teeth; 1 spinous bristle proximal to triangular tooth. 2nd exopodial joint with 4 a-bristles, 8 b-bristles, 1 c-bristles, and 1 d-bristle. 3rd joint with 3 bristles on inner lobe and 2 on outer lobe. 4th and 5th joints fused but separated by 2 small spinous nodes; 4th joint with 2 or 3 bristles, 5th joint with 2.

Sixth Limb (Figure 14d): 4 bare bristles in place of epipodial appendage. Endite I with 2 small, hirsute, medial bristles and 1 long spinous terminal bristle; endite II with 2 or 3 small hirsute, medial bristles and 2 long spinous terminal bristles; endite III with 3 long spinous terminal bristles; endite IV with 3 bristles (1 short, 2 long). End joint with 16 bristles (last 2 hirsute).

Seventh Limb (Figure 14e): Each limb with 4 or 5 (rarely as many as 8) proximal bristles with 2–5 terminal bells, and 9–12 terminal bristles with 2–4 terminal bells; terminus with 4–6 curved finger-like teeth with digitate tips and fine marginal hairs opposite finger-like process with or without digitate tip and with fine marginal hairs.

Furca (Figure 13j): Each lamella with 8 claws decreasing in size proximally along lamella; right lamella slightly anterior to left; small spines on lamellae following claws; all claws with teeth along concave margins; teeth forming medial row on claw 1 larger than teeth forming lateral row; some claws with short hairs along anterior margin.

Bellonci Organ (Figure 14f): Elongate, tapering at tip.

Eyes: Lateral eyes absent. Medial eye small with light brown pigment (Figure 14f).

Upper Lip (Figure 14f): Anterior part with numerous small glandular openings; paired tusks with posteriorly oriented proximal lobe; each tusk with distal and terminal glandular openings.

Genitalia (Figure 14g): Oval ring with attached spermatophore.

Anterior of Body: Small dome-like process present between medial eye and upper lip (Figure 14f).

Posterior of Body: Bare without process.

Y-Sclerite: Typical for subfamily.

Eggs: USNM 157975 with 3 eggs (Figure 13d); BIOGAS VI, DS-71, with 4 eggs; BIOGAS III, DS-41, with 11 eggs; USNM 193166 with 3 eggs; BIOGAS I, DS-12 with 2 eggs; BIOGAS II, DS-32 with 11 eggs and 2 eggs (2 specimens); BIOGAS I, DS-09 (5 specimens) with 7, 9, 9, 9, and 12 eggs.

DESCRIPTION OF ADULT MALE (Figures 12, 15).—Carapace similar in shape to that of female but smaller.

Selvage: Not examined in detail but similar to that of female.

Size: USNM 158592, length 2.38 mm, height 1.46 mm; BIOGAS VI, CP 23a, length 2.53 mm, height 1.51 mm; USNM 193165, length 2.67 mm, height 1.63 mm; BIOGAS II, DS-31, length 2.55 mm, height 1.59 mm; BIOGAS I, DS-07, length 2.48 mm, height 1.42 mm; BIOGAS VI, CP-23a, length 2.51 mm, height 1.46 mm.

First Antenna (Figure 15b–d): Joints 1–6 similar to those of female, except long proximal filaments of sensory bristle of 5th joint broad paddle-like. 7th joint: a-bristle slender, about longer than medial bristle of 6th joint; b-bristle about 3 times length of a-bristle, with stout proximal filament (with large marginal sucker and small protuberance near pointed tip), followed by 2 slender filaments (with 3 or 4 small suckers forming row) and 1 bare filament; c-bristle longer than sensory bristle of 5th joint, with stout proximal filament (with large marginal sucker), followed by 2 slender filaments (each with 4 small marginal suckers), 4 or 5 slender filaments (some with marginal spines), and bifurcate tip. 8th joint: d- and e-bristles about length of b-bristle, bare with blunt tips; f-bristle slightly shorter than c-bristle, with 7 marginal filaments (some with marginal spines); g-bristle as long as c-bristle, with 7 or 8 marginal filaments (some with marginal spines).

Second Antenna (Figure 15e–g): Bristle of 2nd exopodial joint with 8 or 9 marginal spines plus stout subterminal spine; limb otherwise similar to that of adult female.

Mandible (Figure 15h): Dorsal margin of 2nd endopodial joint with about 14 bristles; limb otherwise similar to that of female.

Maxilla: Similar to that of adult female.

Fifth Limb: Anterior side of 1st exopodial joint with additional small spinous outer bristle in addition to 2 distal bristles on female.

Sixth Limb: 3 bristles in place of epipodial appendage; endite III with 3 terminal bristles (1 short between 2 long); end joint with 12 or 13 bristles (posterior 2 hirsute, others with long proximal and short distal spines); limb otherwise similar to that of adult female.

Seventh Limb (Figure 15i): Each limb with 4–7 proximal bristles (2–4 on each side), each with 3–5 bells, and 11 terminal bristles (5 or 6 on each side), each with 2–5 bells; terminus with 4 finger-like teeth with digitate tip and fine marginal hairs opposite finger-like process with or without digitate tip and fine marginal hairs.

Furca, Bellonci Organ, Eyes (Figure 15k), Anterior and Posterior of Body, Y-Sclerite: Similar to that of adult female.

Upper Lip (Figure 15l): Similar to that of adult female, but posterior part of proximal process projecting less on some specimens.

Genitalia (Figure 15j,m): Consisting of 2 or 3 lobes (each bearing small bristles) on each side of body anterior to furca.

PARASITES.—BIOGAS III, DS-41, adult female with cyproniscid isopod and large cluster of isopod larvae; BIOGAS VI, CP-23a, juvenile with cyproniscid isopods; BIOGAS IV, DS-60, adult female with cyproniscid isopod (2 males, 1 female with abundant eggs).

VARIABILITY.—Upper lip: On most specimens whose upper lips were examined, each lip had a small but well-defined proximal, posteriorly oriented, lobe-like process on the tusks. The lobe, however, was absent on many specimens, and specimens without lobes may be more common in certain localities; e.g., 5 specimens (2 females, 1 male, 1 A-1 instar, 1 A-1 female) from CP-23a were without lobes, whereas 1 male from that sample had lobes. The presence or absence of lobes suggests that 2 species might be included in M.quintuplex. At present, I find it expedient to consider the lobate and non-lobate specimens to be 2 forms, rather than 2 species. The upper lip of the holotype has well-defined lobes on the tusks of the upper lip, whereas the upper lip of the illustrated male (Figure 12) is without lobes. Second antenna: The 2nd endopodial joint of this limb on most specimens is at least twice the width of the base of the terminal bristle, but on some specimens the joint is only slightly larger than the base of the bristle; the width of the joint is not related to presence or absence on lobes on the upper lip. Mandible: The basale of the mandibles bears 2 c-bristles. On almost all specimens the small c-bristle is proximal to the long c-bristle, but the opposite relationship was observed on a few specimens. Seventh limb: The finger-like process opposite the comb had a simple tip (blunt or pointed) on some specimens and a digitate tip on others. The digitate tip resembles that of the finger-like processes forming the comb, but this could not be determined with certainty at the magnification at which the 7th limbs were examined (× 100 objective).

COMPARISONS.—The carapace of the new species M.quintuplex resembles those of M. ampla Kornicker, 1970, from the Peru-Chile Trench, and M. optilus (Kornicker, 1968) from the Gulf of Mexico. M. quintuplex differs from both species in being much smaller and in lacking lateral eyes. The tusks of the upper lip on most specimens, but not all, of M. quintuplex differ from those of known species of Metavargula in having a proximal backward oriented lobe.