Juryoecia distoglandula Chavtur & Angel, 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 : 35-38

publication ID	https://doi.org/ 10.11646/zootaxa.2857.1.1
DOI	https://doi.org/10.5281/zenodo.5293185
persistent identifier	https://treatment.plazi.org/id/03DC87FD-EC33-FFF1-6FDD-FF72A3F0FD54
treatment provided by	Felipe
scientific name	Juryoecia distoglandula Chavtur & Angel
status	sp. nov.

Treatment

Juryoecia distoglandula Chavtur & Angel View in CoL n. sp.

( Figs 6–10 View FIGURE 6 View FIGURE 7 View FIGURE 8 View FIGURE 9 View FIGURE 10 )

Synonymy:

1977a Metaconchoecia skogsbergi —Chavtur, p. 145–146 (part).

1977b Metaconchoecia skogsbergi —Chavtur, p. 30 (part).

1977c Metaconchoecia skogsbergi —Chavtur, p. 20 (part).

1992 Metaconchoecia sp. nov. 7—Chavtur, table 2 (list).

Etymology. The specific name “ distoglandula ” is derived from the Latin verb disto, meaning to stand apart, to be distant; and the Latin noun glandula, meaning one of the glands in the neck, tonsils; referring to the position of the LAG, which opens well posterior of the tip of the rostrum.

Holotype. IBM 2822: adult female; length 1.6 mm, appendages mounted on slide and valves in alcohol, in collection of the Museum of Zhirmunsky Institute of Marine Biology, Vladivostok, Russia.

Type locality. RV Vityaz Cruise 39, station 5612 (sample 77) 45º43’N, 153º25’E, depth 5000–6000m, 31 July 1966, using a Bogorov-Rass Net (mouth area 1.0 m²) GoogleMaps .

Paratype. IBM 2823: adult male, length 1.90 mm, appendages mounted on slide and valves in alcohol, also in collection of the Museum of Zhirmunsky Institute of Marine Biology, Vladivostok, Russia. RV Vityaz Cruise 39, station 5617 (sample 121) 45º49’N, 153º33’E, depth 6000–7000 m, 5 August 1966 GoogleMaps .

Additional material. RV Vityaz Cruise 39, 1966: two females (lengths 1.47 and 1.5 mm), immature male (only carapace, 1.45 mm), and three juveniles at station 5612, sample 94, 45º43’N, 153º25’E), depth 4000–5000 m, 31 July 1966 GoogleMaps ; four females (1.35–1.47 mm) at station 5628, sample 223, 43º59’N, 149º46’E, depth 4000–5000 m, 31 August 1966.

Description. Male. Carapace ( Figure. 6A View FIGURE 6 ). The length of the adult specimen is 1.9 mm. The carapace is elongate with a maximum height of 50%CL. The maximum height is behind midlength, so the shell slightly tapers anteriorly. The shoulder vaults are rounded, but weakly developed. The dorsal margin is straight. The posterior dorsal corner has a distinct apex, but the angle is rounded. The posterior and ventral margins merge in a smooth curve, so there is no clear posterior ventral corner. The rostrum is well developed with a pointed tip. The rostral incisure is fairly deep. The RAG opens just below the posterior dorsal corner, whereas the LAG opens on a protuberance that is clearly seen in profile to be situated well behind the tip of the rostrum (39%CL). There is no sculpturing on the carapace of the male but is present on the female carapaces. There are no obvious medial glands.

Frontal organ. The shaft just reaches level with the distal end of the second segment of the A1. However, the capitulum of the holotype has been lost, and where the break occurred is uncertain.

First antenna ( Fig. 6B–D View FIGURE 6 ). The segmentation of the limb is distinct. The a-seta is branched with two basal filaments, both of which are shorter than the main branch. The a-seta is quite short and does not extend back quite as far as the articulation between the first two limb segments. Both the b- and the d-setae have a short row of closelyspaced fine spines of various lengths that are inserted level with the distal ends of the armature on the e-seta. These setae are much longer than the limb, but the ends of both are broken. The c-seta is relatively thin and long 1.5x the combined lengths of the limb’s third, fourth and fifth segments. The e-seta is 1.7x the length of the limb. Its armature consists of 12 pairs of thin, long spines, which lie pointing proximally at an acute angle to the seta. Distally they are close together but become more spaced out proximally. Distal to the armature the e-seta is parallel-sided and unflattened; it ends in a pointed tip. The first segment of the limb contains some dark pigment cells.

Second antenna ( Figs. 6E–G View FIGURE 6 ). The protopodite contains some dark pigment cells. The exopodite is relatively thin and long, 80% the length of the protopodite. The a- and b-setae on the first endopodite segment are bare. The c- and d-setae on the second endopodite segment are of medium length and slim. The e-seta is minute. The hook appendage on the right limb ( Fig. 6F View FIGURE 6 ) has a strongly developed short basal hasp and a long curved distal section. It ends in a rounded swelling with a number of subterminal ridges. The hook appendage on the left limb ( Fig. 6G View FIGURE 6 ) is smaller, with a relatively short and only slightly curved distal section; it has a small terminal swelling with indistinct subterminal ridges. The g-seta, the longest seta, is 4x the length of the first endopodite segment and 5x the lengths of the sensory setae. It is 1.5x and 1.25x the lengths of the exopodite and protopodite respectively. Both the f- and g-setae are slightly flattened terminally.

Mandible ( Figs 6H, I View FIGURE 6 ; 7A–E View FIGURE 7 ). The coxale is short ( Fig. 6I View FIGURE 6 ), about half the length of the endopodite. Its toothed edge has a straight anterior section followed by about 10 teeth, of which the posterior-most tooth is large and triangular ( Fig. 7D View FIGURE 7 ). The distal list has 3 large posterior teeth and is followed by 8–10 small and rounded anterior teeth ( Fig. 7C View FIGURE 7 ). The proximal list is armed with about 23 small and rounded teeth ( Fig. 7C View FIGURE 7 ). The masticatory pad has 4 narrow rounded flaps, which are densely covered with exceedingly fine, rather short spines ( Fig. 6H View FIGURE 6 ), 4 stout teeth, numerous filaments with bifurcated tips, and stiff setules. The toothed edge of the basale has the usual two tubular teeth, of which the posterior one is pointed and carries a few spines, and the second is bluntly rounded and bare ( Fig. 7A, B View FIGURE 7 ). Adjacent to the tube teeth are 6 triangular cutting teeth; the first of which is slightly offset from the others, and lacks the secondary cusps and serrations that are present on the other five. In addition, there is a large inner lateral tooth. The basal endite bears one anterior and two short lateral setae. The epipodite is relatively well developed, wide and rounded on top. The exopodite is reduced to a minute triangular protuberance that carries a long, stout seta with fine setules, which is similar in length to the first endopodite segment ( Fig. 2A View FIGURE 2 ). The first endopodite segment dorsally has a subterminal seta that is short and pilose, laterally a long seta with short setules, and ventrally a shorter seta that also has setules. The second segment has three distodorsal setae and two distoventral setae. The third segment is armed with the usual seven terminal setae; the main claw-like seta is similar in length to the endopodite and somewhat longer than most distodorsal seta on the second endopodite segment.

Maxilla ( Fig. 7F, G View FIGURE 7 ). The basale has no seta. The first endopodite segment is broad. On its anterior side it has four medial setae with short setules, and on its posterior side three setae, and there is a short distomedial lateral seta that extends to just beyond the end of the limb. The distal ventral margin of the first segment is armed with about 10 short spines. The terminal segment is comparatively short and wide. Its anterior claw is about twice as long as the posterior claw. The structures of the precoxal and coxal endites are obscure.

Fifth limb ( Fig. 7H, I View FIGURE 7 ). The epipodial plate carries three groups of four plumose setae. The first endite of the protopodite has a seta with long setules and two shorter setae with short setules. The second endite has 8–9 setae; two are clawlike, and one or two of the others are long setae with long setules; the remaining five are short to medium-length with short setules. The basale has 7 ventral setae, and dorsally a seta with short setules and a long seta with long setules. This long dorsal seta is interpreted as being the remnant of the exopodite by Boxshall (1998) and Kornicker (2003) on the basis of the musculature. The first endopodite segment has two ventral setae and one dorsal seta with short setules. The second segment has three terminal setae; the central seta is long and claw-like and is flanked by two shorter setae.

Sixth limb ( Fig. 8A, B View FIGURE 8 ). The epipodial plate carries three groups of long plumose setae (dorsal to ventral) of 7 (the dorsal-most seta is short), 5 and 5. On the basale there are three short ventral setae and laterally a long seta with long setules and a shorter bare seta. The first endopodite segment has only a tiny ventral seta. The second segment has a minute medial seta on both its dorsal and ventral margins. The terminal segment is armed with the usual three long setae, carrying long setules along their distal quarters.

Seventh limb ( Fig. 8C View FIGURE 8 ). The terminal segment bears the usual two unequal setae (the longer 3x longer than the shorter).

Copulatory appendage ( Fig. 8E View FIGURE 8 ). The appendage is straight and parallel-sided with a rounded tip. Its length is 33%CL.

Caudal furca ( Fig. 8D View FIGURE 8 ). Each lamella bears eight claw setae, and there is an unpaired seta with short setules between the lamellae dorsal to the smallest pair of claw setae. The inner surfaces of the lamellae are covered with fine setules.

Female. Carapace. ( Fig. 9A–F View FIGURE 9 ). The lengths of adult females range from 1.47–1.60 mm (mean 1.52 mm). The maximum height of the shell (50–53%CL) is posterior to midlength, so the carapace tapers anteriorly. In the ventral aspect, the maximum width (43–46%CL) is at midlength. The opening of the LAG varies from 30 to 39%CL behind the tip of the rostrum. The surface of the carapace has a faint sculpturing of fine longitudinal striae. In all other respects it is similar to the carapace of the male.

Frontal organ ( Fig. 9G, H View FIGURE 9 ). The capitulum is fused to shaft. It widens distally and is covered with minute spines. Assuming that these fine spines are indicative of the capitulum region, then the shaft clearly extends well beyond the end of the A1 limb. The whole organ is about double the length of the limb.

First antenna ( Fig. 9H, I View FIGURE 9 ). Each of the sensory setae a–d has a short proximal branch near its base; the side branch on the a-seta is slightly longer than the side branches on the other setae. The e-seta is 2.5x the lengths of both of the sensory setae and the limb. Its trailing edge carries a row of minute spines. The surfaces of the second and third segments of the limb are also covered with minute spines.

Second antenna ( Fig. 9J, K View FIGURE 9 ). The protopodite contains a few dark pigment spots. The exopodite is long, 90% the length of the protopodite. The a-seta on the first endopodite segment is just over half the length of the b-seta. On the second segment there is no c-, d- or e-seta. The terminal setae (f–j) are subequal. They are 75% and 88–95% of the lengths of the protopodite and exopodite, respectively, and three times the length of the first endopodite segment. Distally they become widened and flattened and have pointed tips.

Mandible ( Fig. 10A–C View FIGURE 10 ). The basal endite bears one short seta anteriorly, and one long and 2 short setae laterally. Dorsally the second endopodite segment is armed with three distal setae, two short and slim, and one long and thick. The longest terminal claw seta is almost as long as the endopodite. The distal list on the coxal endite ( Fig. 10C View FIGURE 10 ) has one large stout posterior tooth; otherwise, the characters are similar to the male.

Maxilla. Similar to that of the male.

Fifth limb ( Fig. 10D View FIGURE 10 ). Similar to that of the male except there are ten (rather than nine) setae on the first exopodite segment.

Sixth limb ( Fig. 10E, F View FIGURE 10 ). The limb is similar to that of the male, except:

a. The first endopodite segment bears five long setae with long setules.

b. The setae on the second and third segments are relatively long with short setules.

c. The main terminal seta is considerably longer than the epipodial plate and about half the length of the limb.

Seventh limb ( Fig. 10G View FIGURE 10 ). Proximally the limb is noticeably widened; in all other respects it is the same as in the male.

Caudal furca ( Fig. 10H View FIGURE 10 ). It is similar to that of the male.

Remarks. This species is closely related to J. abyssalis ( Rudjakov, 1962) . Table 6 lists some of the characters that discriminate between the two species.

Distribution. The new species has been caught in the Kurile-Kamtchatka Trench in the depth range 4000– 7000 m. A male specimen that closely resembles J. distoglandula was recently caught in the western tropical Atlantic (RV Ron Brown Cruise 0603, 26 April 2006, MOC 10#7 Net 1, depth 5000– 4000m, position 14° 16.930’N, 54° 21.960’W). It is only 1.36 mm in length, but otherwise not only are its carapace characteristics identical, but also the A1 e-seta has two accessory branches. However, the A1 e-seta armature consists of 20 pairs of slim basally pointing spines, so this is a new species.