Aberrantidrilus stephaniae Martin,, 2015

Aberrantidrilus stephaniae Martin, n. sp.

( Fig. 2 View FIG )

TYPE MATERIAL. — Holotype. MNHN HEL 524 About MNHN , slide 11.019.01, sexually mature, mated specimen. Legit M.-J. Dole-Olivier. Type locality: Bévéra River , Sospel, Mercantour National Park, France (station H2BEV, replicate sample No 1, sample code SED66, Sospel 1), 43°52’41.01”N, 7°26’56.94”E, 372 m a.m.s.l., hyporheic zone in alluvial aquifer, 5.VIII.2009. GoogleMaps

Paratypes. Type locality (station H2BEV, replicate sample No 1, sample code SED66, Sospel 1), 5.VIII.2009 ; IRScNB, I.G. 32392, slide 11.017.01: 1 immature specimen (a) and 2 sexually mature, mated specimens (b, c) ; MNHN HEL 524 About MNHN , slide 11.007.04: 1 mature, mated specimen ; IRScNB, I.G. 32392, vial AB31536628: 10 specimens in absolute alcohol (8 immature, 2 mature and mated, 2 fragments). Type locality (station H2BEV, replicate sample No 2, sample code SED58, Sospel 3), 5.VIII.2009 ; IRScNB, I.G. 32392, slide 11.019.06: 1 mature, mated specimen, slide 11.033.01: 1 immature specimen (b on slide).

OTHER MATERIAL. — Many specimens in absolute alcohol, from unsorted material, mostly immature and/or fragments. Type locality (station H2BEV, replicate sample No 2, sample code SED58, Sospel 3), 5.VIII.2009; IRScNB, I.G. 32392, vial AB31515995. Type locality (station H2BEV, replicate sample No 3, sample code SED 62, Sospel 2), 5.VIII.2009; IRScNB, I.G. 32392, vial AB31515997.

ETYMOLOGY. — The species is named after Stéphanie Marchais, playwright, in memory of the “Binôme #2” experience (“Universcience, Les sens des mots”), a dramatized “Art et science” meeting between a scientist and a dramatist, which led to “Baïkal Amour Magistral”, a play that draws inspiration from the scientific activity of one of us (PM) on oligochaetes from Lake Baikal, and on evolutionary relationships between Oligochaeta and Hirudinea. The name is a genitive.

DISTRIBUTION. — Currently only known from the Mercantour National Park, France, hyporheic habitats ( Fig. 3 View FIG ).

DESCRIPTION

Length of (fixed) holotype 4.5 mm, 23 segments (complete specimen). Maximum width 99-179 µm (in the genital region). Prostomium rounded or slightly pointed, about as long as wide. Segments II-VI with a slight secondary annulation, mostly visible on contracted specimens. Clitellum hardly noticeable, extending over XI-½ XII. Somatic setae 38-43 µm long, 1.5 µm thick, 2-5 per bundle anteriorly, 1-3 per bundle in postclitellar segments. Somatic setae all bifid, with upper tooth of similar length to lower or slightly shorter ( Fig. 2D View FIG [ds, vs]), similar in all bundles. Ventral setae of XI modified into penial setae ( Fig. 2B, D View FIG [ps]), one at each male pore, sigmoid, distinctly bifid, with upper tooth longer than lower, with teeth directed towards anterior end of worm. Penial setae 50-64 µm long, 3.3-3.5 µm thick, with distinct nodulus slightly proximal to middle. Ventral (penial) setae absent on XI in mature paratype MNHN Hel 11.007.04 ( Fig. 2A View FIG ). Male pores ( Fig. 2A, B View FIG [mp]) on prominent, external, protruded porophores ( Fig. 2A, B View FIG [pp]), posterior to middle of XI; penial setae between porophores and mid-ventral line. Spermathecal pores on distinct papillae ( Fig. 2C View FIG [spp]) near, or anterior to, middle of XII, between lateral lines and lines of ventral setae.

Pharyngeal glands in (IV)V-VI. Anterior and posterior sperm sacs projecting to IX and XI, respectively; egg sac extending to XIII. Male genitalia ( Fig. 2A View FIG ) paired. Vas deferens poorly visible, shorter than atrium ( Fig. 2A View FIG [vd]), entering apical end of atrium. Atrium ( Fig. 2A View FIG [a]) slender, spindle-shaped and curved near ectal part, terminating in a retractable pseudopenis, 207-287 µm long, 39-47 µm wide, with 3-6 µm thick outer muscular layer, giving atrium an crumpled external appearance; atrium with granular epithelium and lumen containing scattered bundles of sperm ( Fig. 2A View FIG [sp]); ciliation of inner epithelium not seen. Two prostates attached to atrium. Anterior prostate gland very large, attached by a short stalk to apical end of atrium, near junction with vas deferens. Posterior prostate gland small, attached by a short stalk to ectal end of atrium, at base of pseudopenis ( Fig. 2A, B View FIG [ppr]; gland often barely visible). One pair of spermathecae ( Fig. 2C View FIG ) in XII, with large, elongated, thin-walled ampulla ( Fig. 2C View FIG [spa]), extending into XIII, and short, muscular ducts ( Fig. 2C View FIG [spd]). Sperm as a random mass in ampullae, with amorphous round bodies ( Fig. 2C View FIG [ab]), possibly of secretory origin.

REMARKS

Aberrantidrilus stephaniae Martin , n. gen., n. sp. is the third species of the thalassoid, subterranean freshwater genus Aberrantidrilus Martin , n. gen. It is similar to Aberrantidrilus cuspis n. comb. in nearly all respects, except that the penial setae are distinctly bifid instead of lance-shaped with “sharply pointed tips”, and the bifid somatic setae have teeth of similar length on all segments, instead of having the upper tooth much reduced or absent on the posterior segments.In addition, compared with A. cuspis n. comb., the penial setae are smaller in length and diameter by roughly a factor of two in A. stephaniae Martin , n. gen., n. sp. Despite their similar body length (4.8 vs 4.5 mm, respectively), their penial to somatic setal length ratios are quite different (2.32 vs 1.39) ( Table 2 View TABLE ). Aberrantidrilus subterraneus n. comb. is distinguished from its congeners by the shape of the spermathecae and the location of spermathecal ampullae in XII only, somatic setae with upper tooth shorter and much thinner than lower on all segments, and the penial setae simplepointed, slender and much thinner ( Table 2 View TABLE ).

In their review of groundwater oligochaetes from Southern Europe, Sambugar et al. (1999) reported additional material from France, Italy and Slovenia ( Fig. 3 View FIG ), ascribed to A. cuspis n. comb. in spite of significant differences in penial setae (distinctly bifid and shorter than those of the type material). In this respect, those specimens are most similar to A. stephaniae Martin , n. gen., n. sp., which suggests their attribution to A. stephaniae Martin , n. gen., n. sp. but a proper comparison is hardly possible due to insufficient descriptions (see Table 2 View TABLE ). Giani et al. (2011) recently mentioned “ Abyssidrilus sp. 1 ” from ground waters of Slovenia, which might be conspecific with specimens from Italy (Romana Cave, Trieste) and Slovenia (Škocjanske Cave), previously attributed to Abyssidrilus cf. cuspis by Sambugar et al. (1999), suggesting a complex of near-cryptic species (see also discussion below). However, without re-examining this material, it seems wiser, on the basis of current knowledge, to follow the taxonomic decision of Sambugar et al. (1999) and consider these specimens as conspecific with the form described by Erséus & Dumnicka (1988).