Macrostylis vinogradovae Mezhov, 1992

Riehl, Torben & Brandt, Angelika, 2013, Southern Ocean Macrostylidae reviewed with a key to the species and new descriptions from Maud Rise, Zootaxa 3692 (1), pp. 160-203 : 194

Macrostylis vinogradovae Mezhov, 1992

urn:lsid:zoobank.org:act:7C4763BD-9260-4169-8B1F-F666097CB142 Macrostylis vinogradovae Mezhov, 1992 ; p. 87, Fig. 2 .

Type fixation. Holotype: non-ovigerous female, 2.6 mm, Mc-1279, by original designation.

Type material. Holotype: non-ovigerous female, Mc-1279, DM station 4084-II; paratype: female fragment, 1.2 mm, Mc-1280, DM station 4084-I. All material deposited at the Zoological Museum of the Moscow State University.

Type locality. Southern Ocean, southeastern Weddell Sea, off Kapp Norvegia, Dronning Maud Land, with R/ V Dm. Mendeleev, cruise 43, station 4084-II, 70° 53.17’ S, 15° 04.51’ W; 2,925 m depth; by means of the bottom sampler "Okean".

Type material - Remarks. Only the holotype is complete and the only other specimen is a strongly-damaged fragment of which substantial parts are missing. Further, the paratype was collected from a very different depth (bathyal vs. abyssal). An allocation of both specimens to the same species is therefore put in doubt. The type locality is consequently restricted here to the collection locality of the holotype.

Further records. Southern Ocean, southeastern Weddell Sea, off Kapp Norvegia, Dronning Maud Land, with R/V Dm. Mendeleev, cruise 43, station 4084-I, 70° 40.6’ S, 15° 47.8’ W; 4,335 m depth; by means of the bottom sampler "Okean".

Modified diagnosis. Pereonite 3 posterolateral margins not produced posteriorly. Pereonite 4 wider than pereonite 5, lateral margins convex, posterolateral margins produced posteriorly, tapering, posterolateral setae spine-like, robust. Pleotelson ovoid, waist present, setal ridges visible. Ischium dorsal lobe triangular; apex with 1 prominent seta; distally with no seta. Operculum elongate, subsimilar pleotelson length, distally tapering, ventrally keeled, apical width smaller 0.50 operculum width, apical setae short.

Description female. Body. Length 2.6 mm, subcylindrical. Ventral spines. All spines acute. Pereonite 1 spine prominent. Pereonite 3 spine small, closer to anterior segment border. Pereonite 4 spine directed posteriorly, small, closer to posterior segment border. Pereonite 5 spine prominent, medially. Pereonite 6 spine prominent, closer to posterior segment border. Pereonite 7 spine prominent. Imbricate ornamentation (IO). Pereonites 4–7 IO most distinct at collum.

Cephalothorax. Length 0.84 width, 0.16 body length; frons straight, frontal furrow present, straight, slightly anteriorly to antennulae insertions. Fossosome. Length 0.94 width, 0.23 body length. Lateral tergite margins confluent, ventral surface without keel; sternite margins present, not fully expressed. Pereonite 1. Anterior margin concave. Pereonite 4. Width 1.2 pereonite 5 width, length 0.41 width; pereonal collum present. Lateral margins convex. Posterolateral margins produced posteriorly, tapering. Posterolateral setae bifid, robust, spine-like.

Pereonites 5–7. Posterolateral margin produced posteriorly, rounded; posterolateral setae bifid, robust. Pereonite 5. Length 0.45 width, subequal pereonite 4 length. Pereonite 6. Length 0.70 width, 1.4 pereonite 5 length. Pleotelson. Ovoid, waist present, setal ridges visible, length 0.20 body length, 1.56 width, narrower than pereonite 7; statocysts present, dorsal slot-like apertures present. Posterior apex concave at uropod insertions, posteriorly broadly rounded, convex, length 0.21 pleotelson length.

Maxilliped. Basis length 3.8 width; epipod length 3.1 width, 1.0 basis length; palp width subequal basis width, article 2 wider than articles 1 and 3, article 1 and 3 subequal in length.

Pereopod III. Length 0.47 body length. Ischium dorsal lobe triangular; proximally with 2 setae; apex with 1 prominent, robust, bifurcate, straight seta; distally with no seta. Merus dorsally with 5 setae, ventrally with 3 setae. Carpus dorsally and ventrally with 4 setae respectively. Pereopod IV. Length 0.25 body length.

Operculum. Elongate, length 1.8 width, 1.0 pleotelson dorsal length; apical width 0.43 operculum width; distally tapering, ventrally keeled; with lateral fringe consisting of 11–12 setae, distinctly separate from apical row of setae; with 11 short, pappose setae on apex, completely covering anal opening.

Uropod. Inserting on posterior pleotelson margin; length 1.1 pleotelson length; protopod length 8.2 width, 0.85 pleotelson length, distal margin blunt, endopod insertion terminally; endopod 0.33 protopod length, width at articulation subsimilar protopod width.

Figures

FIGURE 2. Macrostylis scotti n. sp. A – E, holotype adult male (ZMH K- 42990), with ciliate epibionts, photoplate. A, dorsal habitus. B, ventral fossosoma. C, ventral pleotelson. D, ventral cephalothorax. E, ciliate epibionts on right lateral margins of tergites 4 – 5. Scales: A = 0.5 mm, B – D = 0.2 mm, E = 0.1 mm.