Gibbolucina zelee Taylor & Glover 2018, n. sp.
Creators: name: Taylor, John D.
name: Glover, Emily A.
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Mollusca
Bivalvia
Lucinida
Lucinidae
Gibbolucina
Gibbolucina zelee

description: Gibbolucina zelee n. sp.
(Fig. 2A-S)
urn:lsid:zoobank.org:act: 3994D94E-2522-4608-B837-513901FE615B
TYPE MATERIAL. — Holotype. Whole shell, L 15.3 mm, H 14.8 mm, T single valve 4.3 mm (MNHN-IM- 2000-33710). Shell in 70% ethanol rehydrated from dried sample.
Paratypes. From type locality, MNHN-IM- 2000-33711 figured 1 whole shell with body rehydrated (Fig. 2 E-G) L 12.7 mm, H 12.5 mm; 1 dry shell L 17.7 mm, H 16.2 mm; 2 whole shells, L 10.5 mm, H 10.7 mm, L 9.2 mm, H 9.3 mm; unfigured 2 whole shells with bodies reconstituted, L 16.9 mm, H 17.4 mm, (NHMUK paratype 20170401), L 13.7 mm, H 13.8 mm; unfigured 6 whole shells and 3 single valves.
TYPE LOCALITY. — Mozambique Channel, Banc de la Zélée, Expédition BENTHEDI 1977 stn R110, 12°25’6”S, 46°16’2”E, 24 m, 10.IV.1977. Shallow, sandy bottom in the lagoon with dense seagrass beds of Thalassodendron ciliatum (Thomassin et al. 2009).
ETYMOLOGY. — From French for zealous, named for Banc de la Zélée itself named after one of the ships of J. Dumont d’Urville’s Astrolabe Expedition (1837-1840).
OTHER MATERIAL EXAMINED. — Madagascar. Campagne MIRIKY, stn DW 3255, North of Cap Saint-André, 15°48.2’S, 44°43’E, 36-39 m, 1 rv (L 15.3 mm) (MNHN). Campagne MIRIKY, stn CP3287, in front of Baie Narendry, 14°33.7’S, 47°27.9’E, 48-54 m, 1 rv (L 14.6 mm) (MNHN). Toliara, Grand Récif de Tuléar, Andeteky area, outer reef slope, lower platform 24 m sand, Thomassin stn TUL 222, 2 lv (1 broken, and L 4.3 mm), 1 rv (L 10.9 mm) (MNHN). Beloza, Grand Récif de Tuléar lagoon, inner coral reef, coarse sand <1 m, Thomassin stn TUL 257, 1 lv (L 11.1 mm) (MNHN). South (2-3 mi) of Nosy Iranja, 31 mi (50 km) SW of Nossi Bé, 15-18 fthms (27-33 m), muddy sand, stn H, 12 v (ANSP 263071). West (7 mi) of Angorombalo, SW Nossi Bé, 35 fthms (64 m), fine sand and mud, stn H 66, 12 v juveniles (ANSP 261566). West (4 mi) of Nosy N’Tangam, SW Nossi Bé, 20 fthms (37 m), muddy sand, stn H 68, I rv, (L 13.7 mm) (ANSP 260083).
DISTRIBUTION. — Mozambique Channel, Western Madagascar.
DESCRIPTION
Shell small, longer than high, L to 17.7 mm, H. to 16.0 mm, subtrigonal, anteriorly extended, umbones prominent. Thin, lightweight, glossy or waxy shell with thick periostracum; in a rehydrated specimen this is clear, flexible with pleated flaps (Fig. 2E). Ventral edge of periostracum extending beyond the shell margin (Fig. 2G). In dry specimens, periostracum thick and encrusting. Sculpture of irregular, widely spaced, low, commarginal lamellae. Shell often with growth distorsions (Fig. 2H). Protoconch: P1 + P2 = 210 µm, PI 189 µm, with PII a narrow rim with no growth increments (Fig. 2S). Lunule ovate, scooped, symmetrical. Ligament short, set on shallow resilifer. Hinge teeth: LV with two, small, cardinal teeth, RV with a single bifid cardinal. Lateral teeth absent. Anterior adductor muscle scar medium long, detached for ½ of length at an angle of 15°. Posterior scar small, elongate, ovoid. Pallial line entire.Ventral margin smooth, shell interior often thickened particularly across the posterior and around the anterior adductor scar.
Anatomy
Limited observations from a rehydrated body (Fig. 2G) show ctenidia with single thickened demibranchs occupying half of mantle cavity, a vermiform foot, simple posterior apertures lacking papillae and short ventral mantle fusion.
REMARKS
Gibbolucina zelee n. sp. is similar in shape and hinge characters to Gibbolucina trigonula from the Miocene of the Aquitaine Basin, France (Fig. 1O, P). The only other similar species in the Indian Ocean is Megaxinus arabicus Glover & Taylor, 1997 (holotype NMW. Z.1995.009) described from a depth of 58 m off southern Oman. Although this has the overall shape of Gibbolucina species, the hinge has no defined teeth only some irregular folds and the anterior adductor scar is longer, both features similar to Megaxinus transversus (Bronn, 1831).
description: Published as part of Taylor, John D. & Glover, Emily A., 2018, Hanging on - lucinid bivalve survivors from the Paleocene and Eocene in the western Indian Ocean (Bivalvia: Lucinidae), pp. 123-142 in Zoosystema 40 (7) on page 127, DOI: 10.5252/zoosystema2018v40a7, http://zenodo.org/record/3738245