Comprehensive Description

provided by Smithsonian Contributions to Zoology
Metavargula iota

HOLOTYPE.—USNM 137472, ♀, length 2.77 mm. Right valve and some appendages in alcohol; left valve dry, gold plated; remaining appendages on 1 slide.

TYPE-LOCALITY.—Vema Cruise 18, station V–18–113.

ETYMOLOGY.—The specific name from the Greek letter in reference to the relatively small size of the species.


DIAGNOSIS.—Carapace length of female, about 2.77 mm.

Sixth limb: 2 bristles in place of epipodial appendage.

Seventh limb: Each limb with 15 or 16 bristles.

Furca: Each lamella with 8 claws.

DESCRIPTION OF FEMALE.—Carapace elongate with broadly rounded anterior with fairly deep incisur (Figures 70a, 71); posterior with backward projecting caudal process; surface smooth.

Infold (Figures 70b,c; 103): Infold broad in area of caudal process and rostrum, narrow elsewhere; infold behind rostrum with about 14 bristles, of these, bristles at inner end of list longer than others; pair of bristles and 3 single bristles present near inner end of incisur; infold of anteroventral and ventral margin with 42 bristles, spacing between bristles wider along posterior part of ventral margin; list on infold in front of caudal process with 23 to 28 fairly large processes and about 8 small bristles (each bristle generally at base of a process); 2 or 3 minute bristles on infold near tip of caudal process.

Selvage: Similar to that on M. adinothrix.

Size (Figure 67): USNM 137472, length 2.77 mm, height 1.39 mm; height 50 percent of length.

First antenna (Figure 70d): Joints 1 to 3 similar to those on M. adinothrix; sensory bristle of 5th joint with 10 long proximal filaments 2 distal shorter filaments and bifurcate tip; bristle of 6th joint about one and one-half times length of joint, with few short faint marginal spines. Seventh joint: a-bristle bare, slightly shorter than bristle on 6th joint; b-bristle with 5 short marginal filaments, some pectinate; c-bristle with 8 marginal filaments (tip of bristle missing). Eighth joint: d- and e-bristles bare, about one-half length of c-bristle and about one and one-half times length of b-bristles; f- and g-bristles long with about 10 marginal filaments (some pectinate) and bifurcate tip.

Second antenna (Figure 70e,f): Protopodite and endopodite similar to those on M. adinothrix. Exopodite: joints 3 to 9 with basal spines; basal spines smaller on proximal joints; lateral spine on 9th joint much larger than that on 8th; 9th joint with 4 bristles, 3 long, 1 short; joints 2 to 8 with short spines forming row along distal margin; bristle of 2nd joint with about 14 minute spines along ventral margin and about 2 faint proximal spines along dorsal margin, bifurcate tip reaching 8th joint; long bristles on exopodial joints 2–9 with natatory hairs.

Mandible (Figure 70g,h): Coxale endite similar to that on M. adinothrix. Basale: dorsal margin with 1 bare bristle and 2 terminal bristles, shorter of these bare, other with short marginal spines; ventral margin with 2 a-bristles, both with short marginal spines, 1 short b-bristle with short marginal spines, 2 c-bristles (proximal of these short bare, other long with long proximal and short distal marginal spines), and 2 d-bristles (proximal bare, distal long spinous). Exopodite and endopodite similar to those on M. adinothrix.

Maxilla (Figure 70i,j): Coxale with stout plumose bristle. Exopodite broad with usual 3 bristles, proximal 2 bristles with long marginal proximal hairs, terminal bristle with few long spines proximally and short spines distally. Endopodite: cutting edge of 1st endopodite joint with 3 rounded teeth; 2 α-bristles present, outer bristle spinous, inner shorter bristle with widely separated short marginal spines; 3 β-bristles present, 2 outer bristles pectinate along inner margins, inner shorter bristle bare; 2nd joint with 4 a-bristles consisting of 2 slender bare inner bristles and 2 long stout outer bristles (outer of these with about 10 teeth along middle of inner margin, other with about 25 teeth along inner margin continuing to tip of bristle), 3 b-bristles, 3 c-bristles, 3 d-bristles, all pectinate.

Fifth limb (Figure 70k): Epipodial appendage with 43 bristles; distoanterior process of protopodite small; 1st endite with 7 spinous bristles, 2nd endite with 5 large spinous bristles and 1 small bare bristle, 3rd endite with about 6 bristles; main tooth consisting of 6 pectinate teeth, proximal triangular peg and posterior bristle; anterior side of 1st joint with 4 bristles, 2 long, 2 short, all with spines; 2nd endopodite joint with plumose anterior bristle and numerous bristles on margin adjacent to main tooth of 1st joint; inner lobe of 3rd joint with 3 bristles, outer lobe with 2; 4th plus 5th joints united with small spined peg between bristle clusters; 4th joint with 4 or 5 bristles, 5th with 2; small hirsute process present on outer edge of 5th joint near base of bristles observed on right limb only; 3rd to 5th joints hirsute.

Sixth limb: Shape of limb similar to that of M. adinothrix; 2 bristles in place of epipodial appendage; 1st endite with 3 bristles, 2 medial, 1 terminal; 2nd endite with 5 bristles, 3 medial, 2 terminal; 3rd and 4th endites each with 3 terminal bristles; 4th endite slightly longer and narrower than 3rd; end joint with 13 bristles on left, 15 on right of USNM 127472; 2 posterior bristles on end joint hirsute, others with long proximal and short distal spines; medial surface of endites and end joint hirsute; ventral margin and end joint with lateral spines except at bases of 2 posterior bristles; ventral margin with short space between 3 posterior bristles and remaining bristles.

Seventh limb: Each limb with 15 or 16 bristles: distal group with 9 or 10 bristles, 4 or 5 ventral, 5 dorsal, each with 3 to 8 bells; proximal group with 6 bristles, 3 ventral, 3 dorsal each with 3 or 4 bells; terminal comb with 7 elongate recurved annulate teeth with marginal spines and digitate tips; elongate incurved annulate peg with digitate tip present opposite comb; comb teeth and peg similar type to those on M. adinothrix.

Furca (Figure 70l), upper lip, eyes and rod-shaped organ (Figure 70m-o): In general, similar to those on M. adinothrix.

Genitalia: Small sclerotized oval with ovoid Pspermatophore attached (Figure 70q).

DISTRIBUTION.—This species was collected at only one station, Cook Strait, New Zealand, at a depth of 117 m (Figure 63).

Metavargula Species Indeterminate

MATERIAL.—USNM 126215, adult ♀ with unextruded eggs, length 3.91 mm, height 2.24 mm; USNM 126216, ♀ with distorted carapace, length about 4.15 mm; USNM 126217–a, juvenile, length 3.12 mm, height 1.67 mm; USNM 126217–b, 2 juveniles, all from IWSOE, USCGC Glacier, station 0023; USNM 137470, juvenile, length 3.10 mm, height 1.52 mm, from Vema Cruise 17, station V–17–18.
bibliographic citation
Kornicker, Louis S. 1975. "Antarctic Ostracoda (Myodocopina) Parts 1 and 2." Smithsonian Contributions to Zoology. 1-720. https://doi.org/10.5479/si.00810282.163