Parthenina varia (Odé, 1993), Ode, 1993

Pimenta, Alexandre Dias, Absalão, Ricardo Silva & Miyaji, Cintia, 2009, A taxonomic review of the genera Boonea, Chrysallida, Parthenina, Ivara, Fargoa, Mumiola, Odostomella and Trabecula (Gastropoda, Pyramidellidae, Odostomiinae) from Brazil, Zootaxa 2049, pp. 39-66 : 53-55

Parthenina varia (Odé, 1993)

( Figs. 36−43 )

Besla varia Corgan, 1967 (apud Odé, 1993c): unpublished name. Pselliogyra varia Odé, 1993c: 23 , figured page 30.

Types and type locality: the types for this taxon are those specimens studied by Corgan (1967, apud Odé 1993c) fromthe Mississippi Delta, and those by Odé (1993c) from the Gulf of Texas, these presumably deposited at HMNS (not examined); see discussion below.

Material examined: southeast and south of Brazil: -- PADCT expedition: MZSP 89121, sta 6541 [15]; MNRJ 10886, sta 6553 [1]; MZSP 89122, sta 6577 [6]; MZSP 89123, sta 6579 [10]; MZSP 89124 sta 6608 [20]; MNRJ 10887, sta 6608 [4]; MNRJ 10959, sta 6611 [10]; MNRJ 12128, 6635 [6]; MZSP 89125, sta 6631 [22]; MZSP 89126, sta 6635 [25]; MZSP 89127, sta 6641 [5]; MZSP 89128, sta 6631 [1]; REVIZEE expedition: MZSP 89129, sta 6653 [8]; MZSP 89130, sta 6657 [2]; MZSP 89131, sta 6662 [20]; MZSP 89132, sta 6666 [3]; MZSP 89133, sta 6669 [11]; MZSP 89134, sta 6677 [1]; MZSP 89135, sta 6678 [1]; IBUFRJ 13965, REVIZEE Central sta 25A (19o31.11’S, 38o46.06’W, 65m), 28.vi.2001, AG coll. [21]; IBUFRJ 13966, REVIZEE Central sta VV38 (19o44’S, 38o22’W, 71m), 22.ii.1996, NOAN coll [1].

Remarks: Corgan (1967, apud Odé, 1993c) in an unpublished thesis, introduced several names for undescribed pyramidellid species. Later, Odé (1993c) used Corgan´s names for some specimens of Odostomiinae from the Gulf of Mexico, calling one of them Pselliogyra varia and crediting its authorship to Corgan. Odé (1993c) presented an illustration of the shell, quoted Corgan´s description and compared it against his material from the Gulf of Mexico. Therefore, the name “ varia ” was made available by Odé (1993c) for whom its authorship must be acknowledged.

The shells of Parthenina varia from Brazil ( Figs. 36–43 ) are very similar to the illustration and description in Odé (1993c: 23, figure on page 30). There is great intraspecific variation in the rectilinearity of the whorls ( Figs. 36−39 ), with some shells being more convex in profile ( Fig. 39 ); in the expression of the axial ribs on the base, with some shells having strong axials ( Figs. 38−39 ) while others have evanescent ( Fig. 37 ) or almost absent axials ( Fig. 36 ); and also in the strength of the spiral grooves, which are sometimes especially distinct on the base ( Figs. 42−43 ).

Although the shell illustrated by Odé (1993b: 30) has a rectilinear profile very similar to Figure 37 (herein), Odé (1993b) also reported variation in the species, in shape (apical angle and slenderness), sculpturing (number of ribs and development of spirals), and the degree of expression of axial ribs on the base.

A very similar shell was reported and illustrated from Abaco, Bahamas Islands ( Redfern 2001) and termed Odostomia sp. E.

Brazilian shells of Parthenina varia are very similar to some European species included in Chrysallida sensu lato (e.g. Peñas and Rolán, 1998) or in Chrysallida (Parthenina) (e.g. Aartsen, 2000), in lacking the clathrate pattern of the type-species of Chrysallida and having mainly axial ribs with almost smooth interspaces except for a spiral thread on the bottom of the ribs, just above the suture. This pattern is also present in Parthenina obtusa (Brown) , Parthenina pyttelilla and Parthenina interstincta (J. Adams) . As discussed above, some species with similar sculpture have been transferred to Parthenina , as a full genus by Schnder et al. (2003). Following them, we propose the new combination Parthenina varia .

Parthenina varia is distinguished from P. pyttelilla and P. interstincta by its less distinct spiral thread that is closer to the suture, and the more rectilinear axial ribs, whereas they are rather sinuous in the two European species. In these respects, it is more similar to P. obtusa which also has rectilinear axial ribs, but the spiral cord in this latter species is not located in the transition zone between the whorl and the base as in P. v a r i a, but instead this cord is located on the first fifth of the whorl, forming a suprasutural row of squares.

Figures

FIGURES 36 − 43. Parthenina varia: 36, 42 (MZSP 90129); 37 (MZSP 89130); 38 − 39 (MNRJ 12128); 41 (MZSP 89128); 43 (MNRJ 10886). 36 − 39: whole shells (respective lengths: 36: 2.4 mm; 37: 2.7 mm; 38: 2.9 mm; 39: 1.9 mm); 40 − 41: protoconchs; 42 − 43: last whorls. Scale bars: 200 Μm.