Simrothiella margaritacea (Koren & Danielssen, 1877)

Solenopus margaritaceus Koren & Danielssen, 1877: 120 .

MATERIAL EXAMINED. — Corsica (France) • 3 specimens (anterior and posterior regions of the specimens preserved in 95% ethanol. Middle regions used for sclerite preparations and DNA extractions); CORSICABENTHOS 3 (Table 2); 122 m depth; MNHN-IM-2019-18280; GenBank: OR456220; OR458918 (1 microscope slide with sclerites, 1 SEM stub); MNHN-IM-2019-18287; GenBank: OR456221; OR458921 (1 microscope slide with sclerites); MNHN-IM-2019-18286); GenBank: OR458920 (1 microscope slide with sclerites) .

DESCRIPTION

Elongate animal (15 × 1.5-2 mm). With rounded ends, the anterior end being slightly wider than the posterior. White to cream color (Fig. 4E). Cuticle relatively thin with hollow acicular sclerites slightly curved (160 -200 × 3-4 µm) (Fig. 7F) intersecting in two or three layers giving a characteristic hirsute appearance.

REMARKS

The external aspect and sclerites of these three Corsica specimens are distinctive from of Simrothiellidae species and correspond with Simrothiella margaritacea (Scheltema & Schander 2000; fig. 11, 20; Zamarro et al. 2016: fig.1). For the identification of this species, the DNA barcodes were decisive as there were previously available sequences for this species (Fig. 2). Sequences from the Corsica Simrothiella specimens closely matched available ones for this species, and therefore supported our identification. This is important given the existence of at least one undescribed look-alike species for which sequence data are also publicly available. This demonstrates that further development of a DNA barcode library with sequences from confidently identified specimens is essential to improve the accuracy and speed of the identification process in solenogasters (Bergmeier et al. 2017), a group for which numerous “known unknowns” are waiting to be formally described (Todt 2013).

The type locality of S. margaritacea is Boknfjord (Norway) and it has been collected in Norwegian waters (75-115 m) and the NW of the Iberian Peninsula (800 m) (Zamarro et al. 2016) (Table 1). With these three specimens from Corsica, the geographical distribution of S. margaritacea is extended to the Mediterranean Sea (122 m).