Metaconchoecia inflata subsp. lata
Creators: name: Chavtur, Vladimir Grygorjevich
Publisher: name: Zenodo
Year: 2003
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Ostracoda
Halocyprida
Halocyprididae
Metaconchoecia
Metaconchoecia inflata
Metaconchoecia inflata lata

description: Metaconchoecia inflata lata nov. ssp.
(Figs. 45­52)
Etymology. The specific name “ lata”, from the Latin adjective for wide refers to width of the carapace.
Holotype. IBM 2816 – adult male, length 1.15 mm, appendages mounted on slide and valves in alcohol, in collection of the Museum of Institute of Marine Biology, Vladivostok, Russia (together, with paratypes).
Type­locality. SRT Birokan ­ station 185, sample 413, lat. 12º00’ N and long. 94°18.5’ W, depth 200­ 100 m, April 9, 1965. using a Juday’s Net (S = 0.1 m ²).
Paratypes. IBM 2817 – adult male, IBM 2818 – adult male, IBM 280319 – adult female, IBM 2820 – adult female, IBM 2821 – adult female, same station and sample as for holotype; appendages on slide and valves in alcohol.
Records of additional material identified are listed in Appendix.
MALE
Carapace (Fig. 45 A­G). The length of adult specimens range from 1.13­1.20 mm (mean 1.16 mm). Carapace is elongated. Its maximum height is 47­52% of the carapace length (CL), and occurs posterior to the midline. Hence the posterior half of the shell is somewhat larger than the anterior half. The maximum width of the carapace is 50­59% CL and is usual positioned just anterior to midlength; generally the anterior region of the carapace is slightly broader than the posterior region. The shoulder vault is weakly developed and rounded. The dorsal margin is either straight or very slightly V­shaped with the apex just posterior to the insertion of the protopodite of the second antenna. The posterior dorsal corner is a rounded angle with a distinct apex. The posterior margin curves evenly, and the ventral margin is slightly curved, curving smoothly into posterior end. The rostrum is slightly developed and has a pointed tip. The rostral incisure is fairly deep. In ventral view, the sides of the carapace are only gently curved. On the right carapace valve the asymmetric gland opens near the posterodorsal corner. The left asymmetrical gland opens 10.8­ 11.5% (mean 11.1%). Dorso­medial glands are weakly developed. There is no surface ornamentation.
Frontal organ (Figs. 45 I, 46 A­F). The shaft extends beyond the end of the second segment of the first antenna. The proximal half of the capitulum is expanded, with a strongly convex ventral margin, whereas the distal part is wide and parallel­sided. Maximum capitulum height is 29­33% of its length The surface of the capitulum is partially covered with numerous minute spines.
First antenna (Figs. 45 I, J, K; 47 A­C). The segmentation is fairly distinct. The a­seta has relatively thick base and extends back parallel to the limb (except proximally where it loops down and is slightly swollen) beyond end of the limb. The b­seta is slightly shorter than the d­seta and bears some subequal­sized anterior and posterior spines. The c­seta is thin and long subequal or somewhat shorter than the total combined lengths of segments the third to fifth. The d­seta is armed with some closely spaced subequal­sized anterior spines. The most e­seta is about 1.7 the length of the limb. The e­seta armature comprises 9­12 pairs of spines, which lie at an acute angle to the seta. The first segment of the limb contains some dark pigment spots.
A­D – lateral view of right valve of shell, E­H – ventral view of shell, I – frontal organ and 1st antenna, J and K – distal part of 1st antenna.
A­F – frontal organ, G – 2nd antenna, H and I – left clasper of 2nd antenna, J­L – right clasper.
A – furca, B­D – copulatory appendage, E and F – distal part of copulatory appendage, G­L – lateral view of right valve of shell, M­P – frontal organ.
FIGURE 50. Metaconchoecia inflata lata nov ssp. (Female: A­F – specimens from station as for holotype; G – IBM 2821; H, J – IBM 2819; I, K – IBM 2820; Male: L – holotype) A­F – ventral view of shell, G – upper lip, H – frontal organ and 1st antenna, I – 2nd antenna, J – distal part of endopodite of 2nd antenna, K – tooth rows of coxa of mandible, L tooth rows and masticatory pad of coxa of mandible.
A – mandible, B and C – distal part of mandible, D – basal endite of mandible, E – maxilla.
Second antenna (Figs. 46 G­L; 47 D, E). The protopodite has some dark pigment spots. The exopodite is 73­74% the length of the protopodite.The first endopodite segment bears two triangular ridges. The distoventral surface of this segment is not covered with fine hairs. The processus mamillaris is bulbous with a beak­like extension pointing slightly forwards. The b­seta is about twice the length of the a­seta and subequal to the length of the 2nd endopodite segment. The c­ and d­setae are relatively long. The e­seta is minute. The hook appendage on the right limb is strongly developed with a long curved distal section and a number of subterminal ridges. On the left limb the hook appendage is smaller, with a relatively short curved distal section and no subterminal ridges. The sensory h­, j­ and i­setae are about 30% the length of the g­seta. The g­seta is subequal to the protopodite, about 1.3­1.4 the length of the exopodite and 4.2 of the first endopodite segment. The f­ and g­setae are somewhat flattened distally.
Mandible (Figs. 47 F, G; 48 A). The coxale cutting edge has a straight anterior section followed by about 15 teeth. The distal list has one large pointed posterior tooth, followed by 10­11 small teeth. The proximal list is armed with large pointed posterior tooth, followed by about 13­15 small teeth. The masticatory pad bears four narrow rounded flaps (covered with exceedingly fine, rather short and exceedingly dense spines), three stout teeth, numerous filaments (with bifurcated tip) and hairs. The cutting edge of the basale has two tube teeth, the posterior one pointed and with spines, the anterior one thick, rounded and bare; there are followed by six serrated teeth, of which the most posterior lacks or almost lacks secondary cusps. The anterior inner tooth is rounded and slightly serrations. The epipodite is triangular and slightly developed. The exopodite is represented by slight, relatively short and plumose seta. It is somewhat shorter than the first endopodite segment. The dorsal seta on this segment is relatively thick, plumose and about 70% the length of this segment. The longest seta from the three dorsal setae on the second segment is stout and subequal to the main claw­like seta of this limb.
Maxilla (Fig. 48 B). The basale has no seta. The length of the first endopodite segment is about 1.5 times the width. At about the middle of the anterior side there are three shorthaired setae. The posterior side bears four short­haired setae. The disto­medial seta extends beyond tip of the limb. On the ventral surface of this segment there are some short spines. The terminal segment is comparatively long and narrow. The anterior claw is 1.5 times the length of the posterior claw.
Fifth limb (Fig. 48 C). The distal, middle and proximal groups of setae of the epipodial plate consist of four, four and four long and plumose setae respectively and the plate is not (?) covered with some short spines. The first endite of the protopodite bears one long plumose seta and one short short­haired seta, and the second endite carries one long plumose and two short short­haired setae. On the endopodite there are eight or nine setae, two of which are claw­like, two­long and plumose, and remainder are short with short­hairs. The first exopodite segment bears seven ventral setae and one dorsal seta All these are shorthaired setae. The second segment has two ventral and one dorsal short­haired setae. The third segment has two fairly long claw­like setae and a shorter ventral seta.
Sixth limb (Fig. 48 D, E).The distal, middle and proximal groups of setae of the epipodial plate consist of five, five and six (and one additional short) long and plumose setae respectively and the plate is not (?) covered with some short spines. The longer seta on the endopodite is not plumose. On the first exopodite segment there are three short ventral and one plumose long lateral setae. The second segment has a short ventral seta, and the third segment is with a short ventral seta and barely longer dorsal seta. The terminal setae and the limb of the exopodite are subequal.
Seventh limb. The limb is thin, long and bare.
Caudal furca (Fig. 49 A). There are eight pairs of claw­setae and an unpaired seta dorsal to the smallest claw­seta. The inner surface is covered with fine hairs.
Copulatoryl appendage (Fig. 49 B­F). The limb is straight, relatively narrow and 31­ 32% the length of the carapace. Its end is obliquely truncated. The anterior side is distinct or slightly concave near the end. There are three­five oblique muscle bands.
FEMALE
Carapace (Figs. 49 G­L; 50 A­F). The lengths of adult females range from 1.13­ 1.25(mean 1.20 mm). The maximum height of the shell is 49­58% of the carapace length (CL), and its posterior part is considerably larger than the anterior part. Its maximum width (47­57% CL) occurs at or just posterior to the midline. In all other respects it is similar to the carapace of the males.
Frontal organ (Figs.49 M­P; 50 H). The shaft extends well beyond the end of the fist antenna and is about double the combined lengths of the 1st and 2nd segments. The capitulum is distinct separated, slightly separated or fused to shaft. It is rather expanded proximally and tapers to a pointed tip. Its dorsal surface is almost straight. Its ventral surface is usually slightly concave distally. The end is usually slightly downturned, and the surface of the capitulum is partially covered with minute spines.
First antenna (Fig. 50 H) The boundary between second and third segments is distinct. There is no dorsal seta on the second segment. The a­, b­, c­, and d­setae are about a half the length (or somewhat shorter) of the e­seta and somewhat longer than the limb. The eseta is about 2.5 times the length of the limb and bears short posterior spines placed along its distal sections. It tapers to a pointed tip, which is unflattened.
Second antenna (Figs. 50 I, J). The protopodite contains some dark pigment spots. The exopodite is short and about 80% the length of the protopodite. The distoventral corner of the first endpodite segment has one ridge. The a­seta is about a third the length of the b­seta. Neither a c­ nor a d­ setae are present. The f­, g­, h­, i­ and j­ setae are somewhat shorter than half the length of the protopodite, and about subequal to the exopodite, and twice (or somewhat more) as long as the first endopodite segment. They are parallelsided and have rounded tips. The processus mamillaris on each endopodite is similar to the male’s.
Mandible (Figs. 50 K, L; 51 A­D). The limb is similar to that of the male, but differs in following respects: the exopodite seta is somewhat longer than the endopodite segment, the dorsal seta on the first endopodite segment is short, epipodite is wide and developed, the shortest seta from three dorsal setae of the endopodite second is shorter
Maxilla (Fig. 51 E). Similar to that of the male.
Fifth limb (Fig. 52 A, B). Similar to that of the male except there are 7 ventral setae and one­two dorsal setae.
Sixth limb (Fig. 50 A­C).The distal, middle and proximal groups of setae of the epipodial plate consist of five, five and six or seven (and one additional short) long and plumose setae respectively and the plate is covered with some short spines. Two setae on the endopodite are plumose. On the first exopodite segment there are four ventral setae (two long and plumose), one plumose long lateral and one plumose long dorsal setae. The second segment has a short short­haired ventral seta, and the third segment is with one ventral and one dorsal short, short­haired setae. The main terminal seta is somewhat longer than the epipodial plate of this limb.
Seventh limb (Fig. 52 D). The limb is thin, long and bare. The terminal segment bears two setae, one about 3,5 times the length of the other.
Caudal furca is similar to that of the male.
Upper lip (Fig. 50 G). The posterior ventral edge is interrupted by a deep V­shaped notch. On each side of the notch there are some very short spine­like processes
Remarks. Some distinguishing characteristics between M. inflata inflata (Gooday, 1981) and new subspecies are listed in the Table 12.
Distribution. This is known only from the type­locality.
description: Published as part of Chavtur, Vladimir Grygorjevich, 2003, Morphology and distribution of some new pelagic ostracods of genus Metaconchoecia (Halocyprida: Halocyprididae) from the North Pacific, pp. 1-102 in Zootaxa 229 on pages 72-84, DOI: 10.5281/zenodo.156688