Parvidrilus tomasini, 2012

Martínez-Ansemil, Enrique, Châtelliers, Michel Creuzé Des, Martin, Patrick & Sambugar, Beatrice, 2012, The Parvidrilidae - a diversified groundwater family: description of six new species from southern Europe, and clues for its phylogenetic position within Clitellata (Annelida), Zoological Journal of the Linnean Society 166 (3), pp. 530-558 : 544-546

PARVIDRILUS TOMASINI SAMBUGAR & MARTÍNEZ- ANSEMIL SP. NOV. ( FIG. 7 )

Types: Holotype. MCSNVRO1004, entire mature specimen, stained in paracarmine and mounted in Canada balsam. Sa Ucca de su Tintirriolu cave (40°27′08′′N, 8°39′15′′E) Siniscola , Sardinia, Italy, 17.iii.2005, leg. Gianfranco Tomasin, Fabio Stoch, Jos Notenboom.

Etymology: Named after Gianfranco Tomasin, for his important contribution to the knowledge of Italian cave ecosystems.

NEW EUROPEAN SPECIES OF PARVIDRILIDAE 545

Description: Entire mature worm, length 1.2 mm, 24 segments, width 45 Mm at VI, 55 Mm at XII. Prostomium rounded, 15 Mm long, 29 Mm wide at base. Body wall thin (especially in dorsal part), unpapillated; foreign particles adhering to cuticle here and there along body. Numerous transversal rows of thin cutaneous glands per segment. Clitellum weakly developed (about XI- XIII), except for two prominent pads comprising a few cells on lateral sides in XII, just anterior to the transversal setal line ( Fig. 7G , cl).

Dorsal (dorsolateral) and ventral (ventrolateral) setae present from III and posteriorly situated on each segment. Dorsal bundles with two (three) straight, thin single-pointed needles (22–29 Mm long) and one long, thin, and flexible hair setae (120– 200 Mm long) ( Fig. 7A–C, h, n ). Ventral bundles composed of two- three strongly curved crotchets, 20–26 Mm long, with enlarged distal half and doublepronged tip with minute distal tooth, and accompanied by one thin hair seta (95–135 Mm long) only present in III- XI ( Fig. 7A–C, G, h , cr). No modified genital setae; ventral bundles of segment XII with a single bifid crochet.

No eyes. Brain long, extending into segment IV, deeply incised posteriorly. Ventral nerve cord in contact with epidermis, beneath muscles of the body wall. Most setigeral segments with a mid-dorsal glandular pouch opening posteriorly on each segment, on about the transversal setal line; glandular pouches absent from IV- VI.

Digestive tract complete, entirely ciliated. An eversible pharynx, with small dorsal pad set off from oesophagus, followed by a narrow, winding tube extending into IX, with thick muscular walls at about VII- VIII; alimentary canal completed by a gut containing sediment, clearly enlarged from segment XIV ( Fig. 7E, g ). Compact pharyngeal glands present in IV- VI. Digestive tract surrounded by a welldeveloped layer of chloragogen cells from V. Coelomocytes and nephridia not observed.

Two somewhat disaggregated testes attached to septum 10/11 ( Fig. 7A, t ). A few free germ cells and morulae floating in the coelomic cavity of segment XI and in the most anterior part of XII ( Fig. 7A , mo). Sperm funnels hardly observed ( Fig. 7A, f ). Vasa deferentia seemingly present as very thin (about 1.5 Mm wide), long and tightly folded ducts in XII ( Fig. 7A, E , vd). Atria elongate (about 150 Mm long), tubular (15–22 Mm wide), extending into segments XII- XIII, merging below the nerve cord and opening on the tip of a mid-ventral pore (in a small porophore?) located between ventral setal bundles of segment XII ( Fig. 7A, D, a 1 , a 2 , ed). Atria made up by an outer thin muscular layer <1.5 Mm thick, and a nucleated epithelial layer, limited to the proximal and most distal parts of atrial wall. Atrial lumen filled in by a granular material (secretions?, remains of old epithelial cells?), and with a large amount of spermatozoids, their heads orientated towards the distal atrial end, and their long flagella orientated towards the proximal atrial end, with a clear flamigerous aspect ( Fig. 7C–F , gm, sp). Prostate glands absent. Two small ovaries with maturing eggs attached to septum 11/12 ( Fig. 7A, F, o ). A mature egg observed in XIV ( Fig. 7A, e ). Oviducts not observed. A single spermatheca present in XII. Spermathecal ampulla tubular (35 Mm long, about 10 Mm wide), thin walled, and obliquely orientated towards the posterodorsal part of the segment; ampulla followed by a conical, bent duct (about 20 Mm long), beginning with a thick epithelium delimiting a wide lumen, and then tapering, with the lumen becoming very narrow, and ending in a minute pore in an anterior and somewhat lateral position, on left side of the worm. Ampulla full of spermatozoids ( Fig. 7A, C, D , sa, sd).

Remarks: Parvidrilus tomasini sp. nov. is a species with long atria (about eight times longer than wide), and a single spermatheca located in the atrial segment. The most characteristic anatomical features of this species are the tubular shape of the spermathecal ampulla and the well-defined, narrow spermathecal duct. Compared with the other two species that have a spermatheca in segment XII, the atria of P. tomasini are considerably shorter than those of P. stochi and longer than those of P. strayeri (see Erséus, 1999, and remarks below).

Distribution and habitat: Parvidrilus tomasini is known only from the type locality in the Sa Ucca de su Tintirriolu cave (Sardinia, Italy). The cave occurs in an isolated Miocene limestone area surrounded by volcanic rocks of the same age. A small brook runs through the lower gallery in contact with the basaltic floor.

Figures

Figure 1. Parvidrilus meyssonnieri sp. nov. A, left lateral view of genitalia in segments X-XII (holotype). B, ventral view of genitalia in segments XI-XIII (paratype MHNL 3.2). C, hand drawings of the unpaired spherical ampulla and associated cell cluster (from living animal). Abbreviations: a, atrium; am, spherical ampulla; c, clitellum; ccl, cell cluster; ds, dorsal seta; gs, genital seta; mo, morula; mp, male pore; nc, nerve cord; ov, oocyte; sg, setal gland; sp, spermatozoa; st, septum; t, testis (or germ cells); vs, ventral seta. Scale bars = 50 Mm.

Figure 2. Parvidrilus meyssonnieri sp. nov.; scanning electron micrographs. A, left lateral view of anterior part of body showing dorsal and ventral setal bundles, and the absence of setae in II. B, ventral and dorsal setae. C, left lateral view of genital region showing a genital seta and its associated gland (damaged), the single male pore, and the opening of the spherical ampulla. D, left lateral view of genital region showing the left voluminous setal gland, the median ventral depression behind the porophore (not visible on the picture), and the left genital seta in XII (gs). Specimens from ‘Navogne’ (A–C) and ‘La Martinière’ (D) sites. Abbreviations: amo, spherical ampulla opening; ds, dorsal setae; gs, genital seta; mp, male pore; sg, setal gland; vdp, ventral depression; vs, ventral setae. Scale bars: A = 100 Mm; B–D = 20 Mm.

Figure 7. Parvidrilus tomasini sp. nov. A, reconstruction of genitalia. B, setae. C–G, genital region. Abbreviations: a1-a2, atria; cl, clitellum; cr, crotchet; e, egg; ed, ejaculatory duct; f, funnel; g, gut; gm, granular material; h, hair; mo, morula; n, needle; nc, nerve cord; o, ovary; sa, spermathecal ampulla; sd, spermathecal duct; sp, spermatozoa; t, testis; vd, vas deferens; X–XIV, segments. Scale bars = 10 Mm.