Turneroconcha, Krylova & Sahling, 2020

Krylova, Elena M. & Sahling, Heiko, 2020, A new genus Turneroconcha (Bivalvia: Vesicomyidae: Pliocardiinae) for the giant hydrothermal vent clam ‘ Calyptogena’ magnifica, Zootaxa 4808 (1), pp. 79-100 : 81-83

Genus Turneroconcha gen. nov.

Genus N 1—Krylova & Sahling, 2010: 6.

Type species. Calyptogena magnifica Boss & Turner, 1980 .

Derivation of name. The genus is dedicated to the outstanding American malacologist Prof. Ruth D. Turner, one of the authors of the original description of Calyptogena magnifica , in acknowledgement of her investigations of bivalve molluscs. The gender is feminine.

Diagnosis. Shell large, length to 270 mm, subovate-elongate in outline. Equivalve, inequilateral; umbos prosogyrate. No escutcheon and lunular incision. Pallial line starting from postero-ventral margin of anterior adductor scar and ending on postero-ventral margin of posterior adductor scar; weakly marked in its posterior region. Pallial sinus absent.

Ligament strongly developed, external, parivincular. Posterior part of the posterior lamellar layer attached to shelf-like continuation of nymph that deeply submerges below dorsal shell margin. No subumbonal pit.

Hinge teeth radiating. Right valve with strong anterior cardinal (1) and smaller subumbonal cardinal consisting of single posterior 3b ramus. Left valve with subumbonal cardinal tooth consisting of thin 2a ramus, fused by thin low bridge with higher and stronger wedge-shaped 2b ramus. Postero-dorsal cardinal 4b reduced to different degree, sometimes totally. Inner margin of valve thin, without any grooves.

Ctenidia comprising both inner and outer demibranchs; interlamellar septa with a tubular structure in its marginal parts. Exhalant and inhalant siphonal tubes short. Inner valve of inhalant siphon without processes. Inner mantle fold 3 with tentacles. Digestive tract not linear, changing direction twice in midgut.

Species included. The type species only: Turneroconcha magnifica comb. nov. ( Boss & Turner, 1980).

Distribution. Pacific Ocean, the East Pacific Rise from 23ºN to 18ºS, Galapagos Rift, depth 2251–2791 m ( Table 3, Fig. 1 ).

tory, Santa Barbara, USA.

Species Source of material

Ectenagena elongata ( Dall, 1916) RV Western Flyer , ROV Tiburon, Dive T 592, 26° 88’ N, 111°65’ W, 818 m, Gulf of California, 19 May 2003, 4 spms, IORAS

‘ Callocardia ’ stearnsii Dall, 1895 RV Point Lobos, ROV Tiburon, Dive T 3374, 36°48’ N, 121°59’ W, 635 m, Monterey Canyon, 3 June 2009, 5 spms, SBMNH

‘ Calyptogena ’ ponderosa Boss, 1968 RV Atlantis, DSV Alvin, Dive A 4178, 28°07’ N, 89°08’ W, 1075 m, Gulf of Mexico, Mississippi Canyon , 14 May 2006, 5 spms, IORAS

Figures

FIGURE 1. Distribution of Turneroconcha magnifica n. comb. (Boss & Turner, 1980). GR—Galapagos Rift; exact coordinates see in Table 3.