Scleroconcha gallardoi Kornicker, 1971

Chavtur, Vladimir G. & Keyser, Dietmar, 2016, Benthic myodocopid Ostracoda (Philomedidae) from the Southern Ocean, Zootaxa 4141 (1), pp. 1-70 : 20-26

Scleroconcha gallardoi Kornicker, 1971

( Figs. 12–15 )

1971 Scleroconcha gallardoi Kornicker : 194, Fig. 18 .

1975 Scleroconcha gallardoi Kornicker, 1971 —Kornicker: 321–324, Figs. 189, 190 (map), 197–204. 1987 Scleroconcha gallardoi Kornicker, 1971 —Hartmann: 117–118.

1988 Scleroconcha gallardoi Kornicker, 1971 —Hartmann: 143.

1989 Scleroconcha gallardoi Kornicker, 1971 —Hartmann: 235, pl. 3, Figs. 4–8 . 1990 Scleroconcha gallardoi Kornicker, 1971 —Hartmann: 199.

1991 Scleroconcha gallardoi Kornicker, 1971 —Hartmann: 213.

Studied material (coordinates, depth and bottom see Appendix). R /V “Academic Fedorov”, 34th Soviet (Russian) Antarctic Expedition, station 1, sample 8: MIMB 18281—adult female (length 3.79 mm).

52th Russian Antarctic Expedition, station 12, sample 65: MIMB 18276—adult female (4.25 mm), MIMB 18277—adult female (4.16 mm), MIMB 18278—adult female (4.07 mm), MIMB 1 8279—adult female (4.12 mm), MIMB 18280—adult female (4.10 mm), MIMB 18282—immature female (3.40 mm) and MIMB 18 283— immature male (3.26 mm), MIMB 18284a, b and c—adult females (3.81, 3.82 and 3.55 mm).

Additional material. See Appendix.

Diagnosis of adult female. Carapace. Length 3.60–4.35 mm. Carapace reticulate with rib along ventral and dorsal margins, rib lying just within antero-ventral valve margin and present only on anterior half of valve; middle rib extending full length of valve and lying dorsal to central muscle attachments; a lower rib extending almost full length of valve and lying below central muscle attachments. Surface of valves with scattered undivided setae.

Seventh limb. Each limb with 10 setae, 6 in distal group and 4 in proximal group. Terminally limb on comb with 9–17 bare teeth and 1 bare peg present on opposite comb.

Caudal furca. Each lamella with 15 or 16 claws; 3rd claw slender, subequal or slightly longer than 4th claw.

Bellonci organ. Organ elongate with about 22–29 segments at proximal part (include base) and middle.

Medial eye. Large and smooth.

Supplementary description of adult female. Carapace ( Fig. 12 A–J; Plate 2 A–D). Length 3.60–4.25 mm (in literature: 3.76–4.35 mm). Shape, ribs and ornamentation of carapace similar to that of females illustrated by Kornicker (1975: Figs. 197, 201, 202). Middle rib lying below central muscle attachments straight in anterior half. Infold on rostrum with about 12–14 setae forming a vertical row. Antero-ventral inside with about 15 striations and about 20 minute setae in row ( Fig. 12 I). Surface of valves with scattered undivided setae ( Fig. 12 J).

First antenna ( Fig. 13 A, B). Joints 1 to 6 similar to those described by Kornicker (1971: 194). Seventh limb: a-seta somewhat longer than seta on sixth limb; b-seta with 2 proximal and 3 terminal filaments (in Kornicker 1971: 2 and 4 filaments, respectively); c-seta with 5 proximal and 5 terminal filaments; d- and e-setae bare and subequal; f-seta with 4–6 proximal and 5 terminal filaments ( Kornicker 1971: 6 and 4 filaments, respectively); gseta with 5 proximal and 5 terminal filaments; joint 2 to 5 with clusters of setules along ventral and dorsal margins.

Second antenna ( Fig. 13 C–F). Exopodite: first joint with minute elongate process on distal margin; distal margin joints 2–8 with spines in a row and with tiny basal spines; ninth joint with 7 setae consisting of 4 long and 3 short setae (one specimen of the South Shetland Islands with 6 setae). Endopodite 2-jointed: first joint with 4 or 5 proximal (one limb with aberrant proximal seta—Fig. 13 F) and 1 or 2 distal setae, proximal seta in proximal group longer than others; second joint with extremely long, spinous ventral seta barely reaching (or slightly not reaching) terminal margin of exopodite, short bare terminale (on limb it rises from a tubercle—Fig. 13 C, E).

Mandible ( Fig. 13 G, H). Basale with 8–9 ventral setae. Exopodite about 4/5 or 9/10 length of first endopodial joint. Endopodite: first joint with 4–5 ventral setae; dorsal margin of second joint with 5 setae in proximal group 6 setae in distal group and 1 seta between these groups, ventral margin 3–4 setae in subterminal group and 3 in terminal group. End joint with 4 setae and 3 claws.

Maxilla. Anterior of basale with minute short setae. First endopodial joint with 1α- and 5β-setae; second joint with 3a-setae (regular type), 2b-setae (claws), 3c-setae (regular type) and 2d-setae (claws). Endite I with 9 setae, endite II with 6 setae, endite III with 10 setae.

Fifth limb. Epipodial appendage with about 61 setae. Fourth plus fifth joints with 6 or 7 setae.

Sixth limb ( Fig. 14 E–G). Endite I with 3 terminal setae; endite II with 3 or 4 terminal and 1 medial setae; endite III with 8 terminal and 1 medial setae; endite IV with 8 or 9 terminal and 1 medial setae; end joint with 35– 46 setae; 4 or 5 setae present in place of epipodial appendage (one limb with 2 aberrant setae on end joint—Fig. 14 F).

Seventh limb ( Fig. 15 G). Each limb with 10 setae (3+3 distal and 2+2 proximal); each seta with 3–8 (usual 4– 7) bells. Terminal comb with 14 bare teeth (only with 13 on one and 17 teeth on other limb); single bare peg present on opposite comb.

Caudal furca. Each lamella with 15 or 16 claws (on left limb with 13 claws). 3rd claw more slender and subequal or slightly longer than 4th claw.

Bellonci organ ( Fig. 13 A). Organ elongate with about 22–27 segments at proximal part (base included).

Upper lip ( Figs. 12 K; 13 B). Ventrally hirsute.

Anterior process of body ( Figs. 12 K; 13 B). Process large and rounded.

Eggs: 2 specimens of King-George Island with 8 and 18 eggs in brood chamber.

Supplementary description of A- 1 male. Carapace ( Fig. 14 B, D). Length 3.21–3.26 mm. Shape and ornamentation similar, muscle attachments extending almost full length of valve (barely not reaching caudal process).

Second antenna ( Fig. 15 D–F). Endopodite: first joint with 4 subequal setae in proximal group and 1 distal seta; second joint with 1 extremely long spinous proximal seta and about 8 short bare setae in distal group on ventral margin ( Kornicker 1975: 10–12 distal setae); third joint with midlength bare dorsal seta and 2 short terminal setae.

Sixth limb. Endite I with 3 terminal setae; endite II with 3 terminal and 1 medial setae; endite III with 6–8 terminal and 1 medial setae; endite IV with 7 terminal and 1 medial setae; end joint with 27–32 setae; 3 setae present at place of epipodial appendage.

Seventh limb ( Fig. 15 H, I). Each limb with 8 setae, 4 (2+2) in proximal group and 4 (2+2) in distal group. Terminal comb with 3–4 bare teeth (=pegs) and 1 bare peg present on opposite comb.

Caudal furca. Each lamella with 13 claws.

Bellonci organ ( Fig. 15 B, D). Organ elongate, with about 17 segments (base unsegmented), distally spinous, tip rounded and with small terminal spines.

Description of A- 1 female. Carapace ( Fig. 14 A, C). Similar to that of adult female, but slightly elongated. Length 3.26–3.40 mm.

Second antenna. Ninth joint of exopodite with 6 terminal setae.

Caudal furca. Each lamella with 14 claws.

Distribution and ecology. Circumantarctic sublitoral-upper bathyal species. The species has been collected around almost all of the Antarctic continent between 53° and 77°S (as rule south of 60°S; Kornicker 1975): only 3 specimens were found in the Strait of Magellan— 53°49’18”S and 70°25’00”W ( Fig. 1 ). This species has been collected at depths of 4.5 to 458 m, in the temperature range of 1.21° to—0.92°C, on hard and soft substrates: rock, stone, gravel, sand, muddy sand, mud ( Kornicker 1971, 1975; Hartmann 1987a, 1988, 1989, 1990).

Figures

FIGURE 1. Distribution map of species of the family Philomedidae in the Antarctic region and adjacent regions from literature and original data.

PLATE 2. Scleroconcha gallardoi (Female: A, D—MIMB 18284 a; B—MIMB 18284 b, C—MIMB 18284 c), Philomedes heptathrix (immature female, length 1.72 mm: E, F—D / E “ Ob ′ “, 1963, Station E, sample 2, 19 February). A—left valve of carapace in lateral view; B, E—right valve of carapace in lateral view; C—dorsal view of carapace; D, F—details of sculpture in central and ventral areas of carapace.

FIGURE 4. Scleroconcha tuberculata sp. nov. (Female: A, G, I—MIMB 18269; B, F—MIMB 18272; C, D, H—MIMB 18270; E—MIMB 18271). A, B—upper lip, anterior process, medial eye and Bellonci organ; C—medial eye and Bellonci organ; D-G—medial eye and base of Bellonci organ; H—upper lip and anterior process, I—lateral eye.

FIGURE 5. Scleroconcha tuberculata sp. nov. (Female: A, B, D, F, H, J—MIMB 18269; C, I, K— 18272; E, G— 18271; L— MIMB 18270). A—mandible (not all setae shown); B-C—exopodite and details of 1 st endopodial joint and basale of mandible; D—dorsal margin of 2 nd endopodial joint of mandible; E-F—exopodite and detail of 1 st endopodial joint of mandible; G-Ldetail of 2 nd exopodial joint of 5 th limb.

FIGURE 6. Scleroconcha tuberculata sp. nov. (Female: A, C—MIMB 18271; B, D, H—MIMB 18272; E, F—MIMB 18269; G—MIMB 18270). A—exopodial joints 1 – 5 of 5 th limb; B – G—tip of 7 th limb; H—detail of caudal furca.

FIGURE 7. Scleroconcha tuberculata sp. nov. (Male: MIMB 18268). A, B—right and left valve of carapace in lateral view; C—carapace in ventral view; D—rostrum in lateral view; E—infold of rostrum; F—infold of rostrum and anterior detail of carapace; G—pits of middle right valve; H—upper lip, anterior process, medial eye and Bellonci organ; I—distal part of Bellonci organ; J—medial eye and base of Bellonci organ.

FIGURE 8. Scleroconcha tuberculata sp. nov. (Male: MIMB 18268). 2 nd antenna: A—exopodial joint 3 – 9 (setae not shown); B—exopodial joints 1 – 3; C, D—endopodite of left and right limb; E—detail of 3 rd endopodial joint; F— 1 st endopodial joint. Mandible: G, H—basale, exopodite (abnormal on left limb) and endopodite (setae shown only for basale); I—endite of coxale.

FIGURE 12. Scleroconcha gallardoi (Female: A, E—MIMB 18281; B, D, F, G— 18277; C—MIMB 18277; H – J—MIMB 18280; K—MIMB 18276). Carapace: A, D—right valve in lateral and inside view; B, C—left valve in lateral view; E, Gcarapace in ventral view; F—carapace in dorsal view; H—infold of rostrum; I—infold of anterior part; J—ornamentation and setae of middle valve in lateral view; K—upper lip and anterior process.

FIGURE 13. Scleroconcha gallardoi (Female: A, F—MIMB 18276; B, D, G, H—MIMB 18277; C, E—MIMB 18280). A— 1 st, 2 nd and 3 rd joint of 1 st antenna, medial eye and Bellonci organ; B—upper lip, anterior process, medial eye and Bellonci organ; C – F—endopodite of 2 nd antenna; G, H—basale, exopodite and 1 st endopodial joint of mandible.

FIGURE 14. Scleroconcha gallardoi (Immature female: A, C—MIMB 18282; immature male: B, D—MIMB 18283; female: E – G—MIMB 18279). A, B—right valve of carapace in lateral view; C, D—left valve in lateral view; E, F— 6 th limb (not all setae shown; abnormal end joint on panel F); G—abnormal joint of 6 th limb.

FIGURE 15. Scleroconcha gallardoi (Immature male: A – F, H, I—MIMB 18283; female: G—MIMB 18279), S. species (Juvenile: J—MIMB 18285). A—upper lip, anterior process, medial eye and Bellonci organ; B—distal part of Bellonci organ; C— 1 st and 2 nd joint of 1 st antenna (setae not shown) and lateral eye. 2 nd antenna: D—endopodite; E— 1 st and 2 nd endopodial joints; F— 2 nd and 3 rd joint. G – I—tip of 7 th limb. J—left valve of carapace.

FIGURE 18. Philomedes assimilis (Female: A – C—MIMB 18286; D, F, H – J—MIMB 18287; E, G, K, L—ZMH-K- 42264). A, B—setae on rostrum and caudal process of carapace in lateral view; C—detail of ornamentation and setae on central surface of right valve; D—upper lip, anterior process, medial eye, Bellonci organ and 1 st and 2 nd joints of 1 st antenna; E—Bellonci organ; F, G—upper lip and anterior process; H— 2 nd joint of 1 st antenna; I – L—endopodite of 2 nd antenna.