Vityazoecia, 2011

Chavtur, Vladimir G. & Angel, Martin V., 2011, Revision of Metaconchoecia (Ostracoda: Halocyprididae) and the designation of two new tribes Conchoeciini and Metaconchoeciini 2857, Zootaxa 2857 (1), pp. 1-87 : 27-29

VITYAZOECIA Chavtur & Angel , new genus

Synonymy

1982a Conchoecia ‘rotundata’ group—Deevey, p. 148 (part).

1986 Metaconchoecia Granata & Caporiacco —Kempf, p. 498 (part).

1987 Conchoecia goodayi —Chavtur, p. 1258 (part).

1987 Conchoecia —Chavtur, p. 1258 (part)

1992 Metaconchoecia —Kock, p. 68 (part).

1995 Metaconchoecia Kock —Kempf, p. 149 (part).

Etymology. The name is derived from “Vityaz” to commemorate the famous Russian research vessel from which the type species was first sampled, and “-oecia” derived from the Greek word “οƖκοσ” meaning house, from which the terms ecology and economy have been derived, and is the ending that has become standard for Conchoeciinae genera.

Type species: Metaconchoecia goodayi Chavtur 1987

Composition: The genus includes

Metaconchoecia goodayi Chavtur, 1987 .

Metaconchoecia sp.1 aff. Conchoecia goodayi Chavtur, 1987

Conchoecia lunata Deevey, 1982a .

Vityazoecia n. sp 1 aff. V. lunata ( Deevey, 1982a) new record

Vityazoecia n. sp 2 aff. V. lunata ( Deevey, 1982a) new record

Differential diagnosis. The genus includes the species with the LAG opening>30%CL behind the tip of the rostrum. The RAG opens just over 5%CL below the hinge line. The curve of the posterior margin of the carapace is almost smooth but is interrupted by a slight angle just below the PDC. The carapace is covered with a faint sculpturing of fine horizontal striae. In the male, the A1 a seta has two supplementary basal filaments.

Description. Males. Very few species of either species have been collected, and so the description of males given below has been supplemented with details of a male V. n. sp. 1 aff. lunata recently caught at a depth of 4000– 5000m (Ron Brown Cruise 0603, 21/04/2006, 25° 03.367’N, 60° 37.536’W, MOC10#4 net 1).

Carapace. The length range is 1.45–1.50 mm ( Fig. 5 ). The carapace is relatively high (45–50%CL) and quite broad (45%CL). The maximum carapace height is either at midlength or slightly posterior to it. The LAG opens 30– 36%CL behind the tip of the rostrum. The RAG opening is displaced 10–18% of the height down the posterior margin. The rostrum is relatively well developed (Lrost = 9–11%CL) and is a little longer than the incisure (LC3 = 9.5%CL). There is a faint sculpturing of straight lines that run approximately parallel to the ventral and dorsal margins; species of Vityazoecia and Juryoecia are the only Metaconchoeciini to have clear sculpturing on the carapace.

Frontal organ. There is a clear suture between the shaft and the capitulum. The shaft is long (32.5%CL) and also is sutured close to its midpoint. The capitulum is quite long (15%CL), slim, and almost straight; it extends well beyond the end of the A1.

First antenna. The limb is clearly segmented with the length of the first segment being shorter (65%) than the second. Overall, the limb is similar in length (32.5%CL) to the shaft of the frontal organ and is about 2.5x the length of the capitulum. The a-seta is quite long (10%CL) and carries an additional short to medium-length filament, which is inserted near its base in V. goodayi and at midlength in V. lunata . The c-seta is about 6.5%CL, which is double the combined lengths of the third, fourth and fifth segments. The armature of the e-seta consists of 19–22 pairs of stout medium-length spines, which are close together distally and become more spaced out proximally. The e-seta is long (60%CL and 1.5x the length of the limb). The d-seta is either slightly shorter or similar in length to the e-seta, and the b-seta is a little shorter.

Second antenna. The protopodite is quite short 43–44%CL. The first exopodite segment is slim and ~60% the length of the protopodite. It does not have a terminal seta. The swimming setae are relatively long (68%CL in V. n. sp.1 aff. lunata ). Both the long setae on the endopodite are longer than the protopodite (g-seta 56%CL; f-seta 50%CL). They are slightly flattened distally and end in sharp points. The sensory setae (h-, i- and j-) are subequal (15%CL). These setae are simple and without a side branch, but in V. lunata their basal halves are swollen. The c- and d-setae are slim, bare and short, and the e-seta is minute. The hook appendages are terminally rounded; the left hook is, as usual, the smaller. The right hook has a short basal hasp followed by a rounded right angle. It is then straight before curving quite sharply through ~60° before straightening out again.

Labrum. Deeply notched and with few, very short, stubby, fringing setae.

Mandible ( Fig. 2F ). The exopodite is well developed as a process in V. goodayi and bears a long relatively stout seta with long setules; whereas in V. lunata there is the seta with long setules but no process. The toothed edge of the basale has the usual two spine teeth and six triangular cutting teeth, but Deevey 1982a states explicitly and illustrates it as having 7 cutting teeth (her fig 23h). None of the specimens we have examined show this characteristic. The coxale is relatively short, two-thirds or less than the length of the endopodite. The longest terminal seta on the endopodite is quite long (21%CL and 85% the length of the limb).

Fifth and sixth limbs. The fifth limb is similar to those of the other genera, but the sixth limb appears to have only a very short seta at two-thirds length on the ventral surface of the first segment, and a small medial seta dorsally and another ventrally on the second segment. The three terminal setae are subequal 46%CL, and all three distally carry long setules.

Caudal furca. The longest of the eight pairs of spine setae is 16%CL, and there is an unpaired slim seta at the dorsal end of the paired setae.

Copulatory appendage. This appendage is relatively large in V. goodayi 36%CL, but is quite small in V. lunata 21%CL. The anterior margin is straight or very slightly concave, whereas the posterior margin is clearly arched; so the appendage is broadest at midlength and tapers to its rounded tip. There are 3–5 slightly oblique muscle bands.

Females. Carapace. This description has been supplemented with observations on two females sampled at a depth of 2858–2921m in an epibenthic sledge (Polarstern cruise PS61, station 114/4, 17/02/2002, 61° 43.59’S; 60° 42.52’W). Their lengths are 1.42 and 1.50 mm. The carapace is relatively high and slightly elongated. The maximum height is slightly posterior to midlength. The LAG opens 30–36%CL behind the tip of the rostrum. The RAG is displaced 14–15% of the height down the posterior margin. The rostrum is quite large, LC3 is 10–11%CL, and Lrost is 13.5%CL. As in the male, there is a faint sculpturing of longitudinal lines that lie parallel to the ventral and dorsal margins .

Frontal organ. The capitulum and shaft are fused. Taking the slight notch in the dorsal surface to indicate the base of the capitulum, the length of the capitulum is only slightly shorter than the shaft. The whole organ is straight or slightly down-turned with a rounded tip that is finely spinose along the ventral margin in V. lunata . The shaft is similar in length to the A1 limb, so the whole organ is 1.5–2x the length of the A1 (i.e. 34%CL in V. lunata ).

First antenna. The basal segments are fused, but the first segment appears to be about half the length of the second. There is no dorsal seta. The e-seta (25%CL) is nearly double the lengths of the sensory setae (13.5%CL), and 1.5x the limb (17.6%CL). It carries fine spines along its trailing edge distal to the ends of the sensory setae.

Second antenna. The protopodite is quite short (40%CL). The first exopodite segment is relatively thin and long, 60% the length of the protopodite. The length of the complete exopodite is 75% that of the protopodite. The terminal setae on the endopodite are subequal, parallel-sided and pointed. They are relatively long, about 75% the length of the protopodite (i.e. similar to the exopodite), and about 3.5x the length of the first endopodite segment.

Mandible. The structure of this limb is similar to that of the male.

Fifth limb. The ratios of the lengths of the terminal seta (dorsal to ventral) are close to 85:100:60 with the longest seta being 8.5%CL.

Sixth limb. The ratios of the lengths of the terminal setae are close to 70:100:50. The longest, central seta is 12.5%CL.

Caudal furca. Similar to that of the male.

Remarks. A carapace of a male (or an A– 1 male) that closely resembles V. goodayi was found in a deep sample from the North Pacific (RV Vityaz 1966, St. 5612, 45º43’ N; 153º25’ E, 5000– 4000 m). It is identified here as V. sp.1 aff. goodayi ( Chavtur 1987) , since it differs from the type material ( Chavtur 1987) in having the RAG displaced about 12–13% the height (c.f. 17% in V. goodayi ) down posterior margin, and the LC3 is 36% (c.f. 31–32% in V. goodayi ). Otherwise the size and shape of this isolated carapace were consistent with V. goodayi . Specimens of V. lunata , which have been used to help refine the description of the genus, were collected from the RV Polarstern in deep samples collected in the Southern Ocean (a female at Station 80–9, date 23/2/2005, 70° 38.46’S, 14° 42.87’W, depth 3102–3136m, and a male at station 16–10, date 26/1/2002, 41° 07.57’S, 9° 55.97’E, depth 2858– 2921m). Recently, during a Census of Marine Zooplankton cruise to the southwest Atlantic on the RV Ron Brown, another very similar female specimen, designated herein as V. n. sp.1 aff. lunata , was taken in a MOCNESS 10 net ( Wiebe et al. 1976) at 25° 03.37’N, 60° 37.54’W at a depth of 5000– 4000 m. So this species appears to be very widely distributed at deep bathypelagic to abyssopelagic depths. Another female initially identified as C. lunata , but now designated as V. n. sp.2 aff. lunata , was taken at Discovery station 9541#22, date 20/4/1977, at 20° 08’54”N, 21°25’00”W, at a depth of 3780–3870m (within 100m of the sea floor). However this female is 1.70 mm long, and shows a number of minor deviations from the descriptions given above.

Distribution. Pacific Ocean: regions of the Kurile-Kamtchatka, Aleutian and Japan Trenches at depths of 2000–5000 m ( Chavtur 1977c, 1992), in the Pacific sector of the Southern Ocean between 47°– 60°S at depths of 3500–3750 m ( Deevey 1982a), in deep hauls in the N.E. and N.W. Atlantic at depths> 3780m, and in the Atlantic sector of the Southern Ocean in epibenthic sled samples (Polarstern stations16–10 and 80-9 at depths of 2850– 3150 m - see above).

Figures

FIGURE 2. Basal segments of the mandibles of eleven species in the tribe Metaconchoeciini, showing the variations in the extent to which the exopodite is developed; in some species there is a process on which a pappose seta is inserted (indicated by *), but in other species there is no process and only the seta is present. A, Juryoecia distoglandula; B, J. abyssalis; C*, Deeveyoecia bathyrotundata; D*, Rotundoecia teretivalvata; E, Clausoecia pusilla; F*, Vityazoecia goodayi; G*, Metaconchoecia crassiseta; H*, Kyrtoecia kyrtophora; I, Muelleroecia glandulosa; J*, Nasoecia nasotuberculata; L, Austrinoecia isocheira. (Note: the mandibles are not sexually dimorphic, so the sex of the specimen drawn does not have to be specified).

FIGURE 5. Carapace outlines of females of the various forms of Muelleroecia macromma reported in the literature reproduced at identical scales. A, sensu strictu (Müller 1906a); B, M. sp.1 aff. C. macromma Deevey 1974; C, M. sp.2 aff. C. macromma Deevey 1982; D, M. sp.3 aff. C. macromma Poulsen 1973; E, M. sp.4 aff. C. macromma Angel 1981b.