Metaxia sp.

Fernandes, Maurício Romulo, 2024, Triphoridae (Gastropoda) from Martinique sampled by the MADIBENTHOS expedition, with notes on shallow-water species from Guadeloupe, Zoosystema 46 (18), pp. 457-503 : 474-476

publication ID	https://doi.org/ 10.5252/zoosystema2024v46a18
publication LSID	lsid:zoobank.org:pub:650979F1-53CD-4B0A-B9A2-E6B1A49E9C2B
persistent identifier	https://treatment.plazi.org/id/2F0B8D3B-FFA0-D200-FBB0-C7B80760FB1A
treatment provided by	Plazi
scientific name	Metaxia sp.
status

Treatment

Metaxia sp.

( Fig. 10 View FIG )

MATERIAL EXAMINED. — Martinique. MADIBENTHOS. ‘Sud Atlantique’ • 1 sh; sta. AB181; MNHN.

GEOGRAPHIC DISTRIBUTION. — Only known from Martinique.

BATHYMETRIC DISTRIBUTION. — Only known from 22 m.

REMARKS

The single available shell of Metaxia sp. has a faint axial sculpture and a protoconch with 2.5 whorls (measuring 0.32 mm long, 0.31 mm wide), and its embryonic shell has a distinct, abapical zigzag spiral cord and a smaller, adapical spiral cord bordering the adapical portion of the whorl ( Fig. 10D View FIG ). It could be an atypical shell of M. rugulosa , regarding the wide variation in the embryonic shell of this species ( Rolán & Redfern 1996), although Caribbean shells of M. rugulosa are usually white and have a coarse axial sculpture ( Rolán & Fernández-Garcés 2007, 2008; Lee 2009). Most Brazilian shells of M. rugulosa are brown ( Fernandes & Pimenta 2011, 2020), similarly to Metaxia sp. ( Fig. 10A, B View FIG ), which demands further studies – desirably with genetic evidence. Metaxia propinqua Rolán & Fernández-Garcés, 2008 , from southern USA, has shells entirely white or with a white protoconch and light brown teleoconch. The white paratype of M. propinqua illustrated by Rolán & Fernández-Garcés (2008: fig. 1E-G) seems a typical shell of M. rugulosa , contrary to the bicolor holotype.

Another remarkably similar species to Metaxia sp. is Metaxia quadrata Faber, 2010 , described from Aruba, based on a single (juvenile) shell. This species was described as yellowish brown, and the axial sculpture of the teleoconch is much faint, as observed in Metaxia sp. ( Faber 2010). The apparent single difference between them is that M. quadrata has three spiral cords (vs two in Metaxia sp. ) on the first protoconch whorl. Because Metaxia species are mainly differentiated by subtle differences in protoconch morphology, more material from the Lesser Antilles is required to properly evaluate the taxonomy of this morph from Martinique.