Conchoecia Dana, 1849

Chavtur, Vladimir G. & Bashmanov, Alexander G., 2018, Pelagic ostracods of the new subtribe Conchoeciina (Ostracoda, Crustacea) from the North Pacific, Zootaxa 4516 (1), pp. 1-127 : 10-11

Genus Conchoecia Dana, 1849 (part)

1849 “Conchaecia” —Dana: 51;

1890 Conchoecia Dana—Claus : 7 (partly);

1956 Conchoecia Dana—Sylvester-Bradley & Iles: 213–216;

1973 Conchoecia Dana—Poulsen : 123–124 (partly);

1906 Conchoecia Magna-Gruppe—Müller: 98–99 (partly);

1968 Conchoecia Magna-Groupe—Deevey: 76–77 (partly);

1969 Conchoecia Dana—Angel : 51–56;

1973 Conchoecia Dana—Poulsen : 123–124 (partly);

1979 Conchoecia Dana—Martens : 317 (partly);

2012 Conchoecia Dana –Drapun & Smith: 53 (partly).

Type-species.— Conchoecia magna Claus, 1874 .

Composition.— This genus includes:

Conchoecia magna Claus, 1874

Conchoecia aff. magna (sensu Martens, 1979)

C. subarcuata Claus, 1890

Conchoecia rudyakovi Chavtur , sp. nov.

Conchoecia angustipilata Chavtur , sp. nov.

Conchoecia sculpta Chavtur , sp. nov.

All these species (except C. magna ) were found in the analyzed material and described below. Note three of the species included in this genus by Poulsen (1973) and by Müller (1906) in his ‘ Magna’ group will be re-classified in new genera below.

Since previous descriptions of this genus (see synonymy) include species ( Conchoecia macrocheira , C. lophura , C. parvidentata , C. hyalophillum, Porroecia porrecta , P. spinirostris , P. vibekensis , P. crassispina , P. parthenoda , P. pseudoparthenoda , Obtusoecia obtusata , O. antarctica , which according to our revision belong to new genera ( Macrochoecilla Chavtur , gen. nov., Lophuroecia Chavtur , gen. nov., Parvidentoecia Chavtur , gen. nov., Hyalocoecia Chavtur , gen. nov. and Parthenoecia Chavtur , gen. nov.), we propose a new diagnosis for this genus.

Diagnosis of genus. Adult male. Carapace. Length is between 1.40–2.55 mm. The carapace is rectangular and is not tapered anteriorly. Locations of asymmetrical glands are usual for the subtribe. There are no lateral corner glands.

Frontal organ. The stem is straight. The capitulum has a broad rounded tip.

First antenna. The armature of seta-e has a comb with 10–23 distal pairs of long or short straight spines and 12–20 proximal alternated spines ( C. subarcuata bears only paired spines); all spines directed proximally.

Second antenna. Seta-b of the endopodite bears one to five long posterior fine filaments and zero to four medium-length and two or three long anterior filaments. Right clasping organ is almost squared with a rounded (swollen or not), pointed or spine-like tip. Left clasping organ is right-angled (except for C. subarcuata : both clasping organs have an acute-angled shape) with a pointed tip.

Mandible. The epipodite bears a medium-length seta (except C. subarcuata , which has a rudimentary spinelike seta here). The ventral margin of the first endopodite segment has one long seta and two short setae.

Maxilla. The first endopodite segment has six anterior setae and three posterior setae. All anterior setae are located along the segment margin.

Fifth limb. Usual for the subtribe.

Sixth limb. The ventral margin of the basale has five setae: one or two long (one of which is plumose) proximal setae and two to four short bare distal setae ( Figs. 6B, C ; 10J ; 18H ; Drapun & Smith 2012: Pl. 19M).

Caudal furca. An unpaired seta is present.

Copulatory limb. It is spindle-shaped, with a rounded tip, tapered to the end and broadest at the middle.

Adult female. Carapace. Length is between 1.63–2.70 mm. It has a rectangular outline that is more rounded than the male and barely tapers anteriorly.

Frontal organ. The stem is straight. The capitulum is bent down, its tip is elongated, pointed and bent downwards.

First antenna. The dorsal seta on the second segment is developed. Seta-e is bare proximally and with short spinules distally or in the middle part.

Second antenna. The first endopodite segment is about 25–28%, 34–38% and 41–50% the length of setae-g, -f and –h, respectively. Terminal setae on the endopodite slightly taper toward the pointed tip.

Mandible, maxilla, fifth limb and caudal furca are similar to those of the male.

Sixth limb. The basale has five ventral plumose setae and without or with a lateral plumose seta.

Figures

FIGURE 6. Conchoecia rudyakovi Chavtur, sp. nov. (Adult male: A—MIMB 18344/9; B, E, and G—MIMB 18344/14; C— MIMB 18344/2; D—MIMB 18344/6; F—MIMB 18344/7. Adult female: H—MIMB 18344/12; I, L, and M—MIMB 18344/ 10; J—MIMB 18344/19; K—MIMB 18344/18; N—MIMB 18344/11). A—sixth limb; B—proximal part of sixth limb; Dseventh limb; E and F—copulatory appendage; G—distal part of copulatory appendage; H–K—right valve of carapace in lateral view; L and M—carapace in ventral view; N—carapace in posterior view.

FIGURE 10. Conchoecia angustipilata Chavtur, sp. nov. (Adult male: A–K—MIMB 18346/1). A and B—distal part of endopodite on right and left second antenna; D—mandible (setae not shown); D and E—epipodite of mandible; F—tooth edge of basale endite; G—distal part of maxilla; H—fifth limb; I—sixth limb; J—proximal part of sixth limb; K—furcal appendage.

FIGURE 18. Conchoecia sculpta Chavtur, sp. nov. (Adult female: A and K—MIMB 18345/4. Adult male: B, H, and I— MIMB 18345/1; C–G, J, L, and M—MIMB 18345/2). A—epipodite of mandible; B—tooth of basale endite; C and D—fifth limb; E—coxale and precoxale of fifth limb; F—sixth limb; G and H—proximal part of sixth limb; I and J—seventh limb; Kdistal part of seventh limb; L—copulatory appendage; M—distal part of copulatory appendage.