Eucalathis daphneae, Bitner & Logan, 2016

Bitner, Maria Aleksandra & Logan, Alan, 2016, Recent Brachiopoda from the Mozambique-Madagascar area, western Indian Ocean, Zoosystema 38 (1), pp. 5-41 : 18

publication ID	https://doi.org/10.5252/z2016n1a1
publication LSID	urn:lsid:zoobank.org:pub:96BFE594-1B39-4541-9441-181617BD4CF9
DOI	https://doi.org/10.5281/zenodo.4579075
persistent identifier	https://treatment.plazi.org/id/1438903A-BBB0-4F65-95FC-08A56E1AAB1D
taxon LSID	lsid:zoobank.org:act:1438903A-BBB0-4F65-95FC-08A56E1AAB1D
treatment provided by	Felipe (2021-03-03 16:45:34, last updated by Plazi 2023-11-01 22:51:56)
scientific name	Eucalathis daphneae
status	sp. nov.

Treatment

Eucalathis daphneae View in CoL n. sp.

( Fig. 10 View FIG E-O; Table 9)

TYPE MATERIAL. — North-West Madagascar. MIRIKY, stn DW 3234, holotype ( MNHN IB-2013-61 ; Fig. 10 View FIG F-J). — Same data, stn DW 3196, paratypes ( MNHN IB-2013-62 , 63 ; Fig. 10E View FIG , K-O) .

TYPE LOCALITY. — Madagascar, MIRIKY, stn DW 3234, 13°27’S, 47°55’E, 187- 247 m.

DIAGNOSIS. — Eucalathis with single, broad, rounded costae nearly smooth in anterior half, and incomplete loop.

MATERIAL EXAMINED. — North-West Madagascar. MIRIKY, stn DW 3196, 8 bivalved specimens. — Stn DW 3234, 2 bivalved specimens, 1 ventral valve, 1 dorsal valve.

DEPTH RANGE. — 187-249 m

DESCRIPTION

Shell small (maximum observed length 5.9 mm), ventribiconvex, widely subtriangular in outline. Shell surface covered with 10-12 strong, single, rounded costae. Costae weakly beaded posteriorly, nearly smooth in anterior half except where crossed by elevated growth lines; intercostal spaces wide. Anterior commissure rectimarginate. Hinge line slightly curved. Beak low, suberect. Foramen large, subcircular, mesothyrid; deltidial plates small, triangular ( Fig. 10E, G View FIG ). Ventral valve interior with small teeth; pedicle collar wide. Dorsal valve interior with massive inner socket ridges extending beyond margin. Cardinal process distinct. Crura long, slender; crural processes short, can be slightly incurved. Loop short with an incomplete transverse band ( Fig. 10 View FIG I-O). Low, short median ridge visible on inner dorsal valve. Inner margin of both valves crenulated.

REMARKS

In size, outline and ornamentation the new species described here is most similar to Eucalathis rotundata . In the strong costation E. daphneae n. sp. also resembles E. rugosa Cooper, 1973 , differing in size and outline, as well as in the character of costae. E. rugosa possesses beaded, strongly tuberculate ribs ( Cooper 1973c; Laurin 1997; Bitner 2008, 2009, 2010); in E. daphneae ribs are nearly smooth. However, the species described by Cooper (1973c, 1981a) have a typical loop for the genus, whereas in all specimens collected in North-West Madagascar the loop has an incomplete transverse band.

Among Recent representatives of chlidonophorids only in the species Melvicalathis macroctena (Zezina, 1981) may the loop be incomplete ( Zezina 1981b; Lee et al. 2008), however, it possesses broad, triangular in cross-section costae with smooth ridges without any tubercles, differing greatly from E. daphneae . In the fossil chlidonophorids an incomplete loop is observed only in the Eocene-Oligocene genus Orthothyris Cooper, 1955 (see Bitner & Müller 2015).

References

BITNER M. A. & MULLER A. 2015. - Brachiopods from the Silberberg Formation (Late Eocene to Early Oligocene) of Atzendorf, Central Germany. Palaontologische Zeischrift 89: 673 - 688.

COOPER G. A. 1973 c. - Fossil and Recent Cancellothyridacea (Brachiopoda). Science Reports of the Tohoku University, second series (Geology), Special Volume (Hatai Memorial Volume) 6: 371 - 390.

COOPER G. A. 1981 a. - Brachiopods from the Southern Indian Ocean (Recent). Smithsonian Contributions to Paleobiology 43: 1 - 93.

LAURIN B. 1997. - Brachiopodes recoltes dans les eaux de la Nouvelle Caledonie et des iles Loyaute, Matthew et Chesterfield, in CROSNIER A. (ed.), Resultats des Campagnes MUSORSTOM, vol. 18. Memoires du Museum national d'Histoire naturelle 176: 411 - 471.

LEE D. E., GREGORY M. R., LUTER C., ZEZINA O. N., ROBINSON J. H. & CHRISTIE D. M. 2008. - Melvicalathis, a new brachiopod genus (Terebratulida: Chlidonophoridae) from deep sea volcanic substrates, and the biogeographic significance of the mid-ocean ridge system. Zootaxa 1866: 136 - 150.

ZEZINA O. N. 1981 b. - New and rare cancellothyroid brachiopods. Trudy Instituta Okeanologii 115: 155 - 164 [in Russian with English summary].

Figures

FIG. 10. — A-D, Eucalathis magna Cooper, 1981, ventral, dorsal, lateral and anterior views of complete specimen (MNHN IB-2013-60), South Madagascar, sector of Manantenina, stn DW 3529, 402-407 m; E-O, Eucalathis daphneae n. sp., North-West Madagascar, MIRIKY, SEM: E, inner view of ventral valve (MNHN IB- 2013-62), paratype, West of Cap d’Ambre, stn DW 3196, 238-249 m; F-J, dorsal view of complete specimen, enlargement of umbonal part (G) and anterior view to show rounded ribs (H), and inner view of dorsal valve (I, J) of the same specimen to show cardinalia and loop, holotype (MNHN IB-2013-61), West of Nosy Be, stn DW 3234, 187-247 m; K-O, inner view of dorsal valve (MNHN IB-2013-63), enlargement (L) and tilted (M) views of posterior part,and a fragment of incomplete transverse band (O), paratype, stn DW 3196, 238-249 m. Scale bars: A-D, 5 mm; E, F, H, I, K, 2 mm; G, J, L,1 mm; M, 500 µm; O, 200 µm.