Simrothiella margaritacea ( Koren & Danielssen, 1877 )

Cobo, M. Carmen, Farris, William J. & Kocot, Kevin M., 2024, New data on the biodiversity of Solenogastres (Mollusca, Aplacophora) in the Mediterranean Sea: findings from the program “ Our Planet Reviewed ” Corsica 2019 - 2022, Zoosystema 46 (21), pp. 543-576 : 570-571

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).

Figures

FIG. 4. — Habitus of A, Tegulaherpia cf. myodoryata (photo of the living animal – MNHN-IM-2019-16176); A’, Tegulaherpia cf. myodoryata (photo of the preserved specimen – MNHN-IM-2019-16176); B, Eleutheromenia sierra (Pruvot, 1890) (photo of the preserved specimen – MNHN-IM-2019-1749); C, Pruvotia cf. sopita (photo of the preserved specimen – MNHN-IM-2019-1744 – on Sertularella sp.); D, Unciherpia hirsuta García-Alvarez, Urgorri & Salvini-Plawen, 2001 (photo of the living animal – MNHN-IM-2019-18279); E, Simrothiella margaritacea (Koren & Danielssen,1877) (photo of the preserved specimen – MNHN-IM-2019-18280). Scale bars 1 mm. Symbols: arrow, copulatory stylets; stars, anterior end of the animals.

FIG. 7. — SEM images of the sclerites of A-D, Nematomenia banyulensis (Pruvot, 1890) (MNHN-IM-2019-1747); E, Tegulaherpia cf. myodoryata (MNHN- IM-2019-16176); F, Simrothiella margaritacea (Koren & Danielssen,1877) (MNHN-IM-2019-18280); G, H, Dorymenia vagans (Kowalevsky & Marion,1887) (MNHN- IM-2019-18274); I, Anamenia gorgonophila (Kowalevsky, 1880) (MNHN-IM-2019-18270). Scale bars: 20 µm.

FIG. 2. — Maximum likelihood phylogenetic reconstruction based on COI. MNHN CORSICABENTHOS specimens are shaded with colors corresponding to those used in Fig 1. BOLD (ALPNB #s) and NCBI accession numbers precede species names for publicly available sequences and both NCBI accession numbers and museum catalog numbers precede the species names for the Corsica specimens. Symbols: *, the taxa considered as reference sequences based on Kocot et al. (2019); gray blocks, species delimitation results according to Assemble Species by Automatic Partitioning (ASAP, Puillandre et al. 2021).