Troglodrilus jugeti, Achurra, Ainara, Chatelliers, Michel Creuze Des & Rodriguez, Pilar, 2012

Achurra, Ainara, Chatelliers, Michel Creuze Des & Rodriguez, Pilar, 2012, Troglodrilus jugeti n. sp. (Annelida, Clitellata, Tubificinae), a new stygobiont oligochaete species from south-western Europe, Zootaxa 3229, pp. 35-46 : 39-43

Troglodrilus jugeti n. sp.

( Figures 3 A, 4A–F and 5A–B; Table 1)

Troglodrilus galarzai ( Giani & Rodriguez, 1988) : Juget et al., 2006 (partim): Figures 3 , 4 , 5 , 7, 8, 9, 10, 11 13, 14 and 15; Timm, 2009 (partim); des Chatelliers et al., 2009 (partim).

Tubificoides galarzai: Giani et al., 2001 (partim).

Holotype. MHNL 44002205: A dissected worm, stained in paracarmine and mounted in Canada balsam. Type locality. Subterranean gallery of Montgelas, département du Rhône, France (UTM coordinates X: 0 632161, Y: 5488304, Z: 375).

Paratypes. MHNL 4400224: one dissected specimen from the type locality (3 June 1998). MHNL 44002206, MHNL 44002207 and MHNL 44002208: 3 whole-mounted specimens from the type locality (3 June 1998). Other material. MHNL 44002201, MHNL 44002202 and MHNL 44002203: 3 sectioned specimen from Crotot cave (31 January 2001). MHNL 44002209–44002219: 11 whole-mounted specimens from Crotot cave (31 January 2001). In the collection at the University of the Basque Country (UPV/EHU): 4 dissected specimens (only anterior parts, posterior parts were used for molecular analysis) and 3 specimens preserved in alcohol 70%, all of them from Montgelas gallery (26 October 2006).

Other localities. Crotot cave, northeast of Besançon, Département du Doubs, France (UTM coordinates X: 1208208, Y: 5297684, Z: 411).

Etymology. Named after Dr. Jacques Juget for his contribution to the study of groundwater oligochaetes and, in particular, to the taxonomy of the genus Troglodrilus .

Description. Segment number 25–57. Body diameter in segment V 225–300 µm and 280–441 µm in segment XI. Prostomium conical, 100–115 µm long and 160–175 µm wide. Body wall with glandular epidermis. Clitellum from the end of segment X to segment XII. Spermathecal pores lateral, located close and dorsal to ventral bundles of chaetae in segment X. One pair of male pores open next to ventral bundles of chaetae in segment XI.

Dorsal bundles of chaetae consist of hispid hair chaetae and pectinate chaetae ( Fig. 4 in Juget et al., 2006). In preclitellar segments, 1–6 hairs per bundle, 84–247 µm long; and 1–5 pectinate chaetae per bundle, 28–65 µm long, with 2–5 stout intermediate teeth. In posterior segments, 1–2 pectinate chaetae per bundle. Ventral chaetae bifid, with distal tooth longer than proximal ( Fig. 5 in Juget et al. 2006); in anterior segments 1–6 (28–73 µm long) chaetae per bundle, in postclitellar segments 2–3. Ventral chaetae increase in size posteriad from segment II, reaching a maximum length in segment VI or VII; chaetae are shorter and of similar length in the rest of the segments. No modified genital chaetae.

Coelomocytes not observed within the coelomic cavity. Pharyngeal glands from segment (II) III back to segment VI in specimens from Crotot and to segment (VI) VII in specimens from Montgelas. A layer of chloragogen cells covers the digestive tract, from segment VI backwards. Gut dilatation in VIII.

One pair of testes in X and one pair of ovaries in XI. Sperm sacs extend forward to segment IX and backward to segment XII. Egg sac can reach segment XIV. Male funnels attached to the septum in 10/11. Vas deferens moderately long (somewhat longer than the atrium + penial sac), ciliated and about the same diameter (20 µm) throughout its length. Comma-shaped atria in segment XI ( Fig. 3 A), up to approximately 250 µm long, and 50–55 µm diameter at the junction with the prostate. Vas deferens enters the apical end of the atrium. Atrial epithelium is organised in two layers: a densely granulated layer of epithelial cells at the concave side of atrium, where the prostate joins the atrium (but of different histology); and a light layer of non-granulated cells at the convex side and along the distal section of the atrium. Atrium opens into a penial sac, 64–100 µm long and 50–65 µm wide, internally lined by 2–3 µm thick cuticle forming a hemispherical collar ( Fig. 3 A and 4A–F), which is easily observable in whole mounts. Penis within a tubular cuticular stalk, 53–75 µm long, with a wide ental section (24– 50 µm diameter) and narrowing at about the median length (20–30 µm). Surface of the penial sheath smooth, devoid of any fold ( Fig. 4 A–F). One pair of spermathecae in segment X. Spermathecal ampulla oval. When completely mature, one ampulla can extend to segment IX and the other one to segment XI. Spermathecal duct 125–150 µm long, and 20–30 µm wide along all its length, excluding the ectal part, where the duct widens to 38–62 µm forming an elongated vestibular section ( Fig. 5 A–B). Several spermatozeugmata (ca. 250 µm long, 30 µm maximum diameter) fill each ampulla in mated specimens.

Distribution and habitat. Limited to groundwaters, in the gallery of Montgelas and in Crotot cave. Montgelas gallery is a small and shallow artificial cavity (<50 m length), near the Saône valley. Jurassic limestone, but little karstified and no cave or drainage systems. Clayey sediment, water temperature 11ºC, specific conductivity 640 µS/cm. Crotot cave is a large cavity (5,800 m length), on a plateau near the valley of the Doubs River. Middle Jurassic limestone. Abundant, fine clayey sediment in the river. Water temperature 10ºC, specific conductivity 550–570 µS/cm.

Taxonomic remarks. The diagnosis of new species agrees with the description of the genus Troglodrilus Juget et al., 2006 . The most important features that distinguish T. jugeti n. sp. from T. galarzai are: (1) the spermathecal vestibule is elongated (only up to two times wider than the duct diameter) ( Fig. 5 A–B) while it is spherical or bulbous and wide (up to> 4 times the duct diameter) in T. galarzai ; (2) the penial sac is smaller than in T. galarzai ( Table 1); (3) the space between the collar and the ental part of the tubular stalk of the penial sheath is wider than in T. galarzai ; and (4) the penial sheath is smooth while several longitudinal folds are present in penial tubular stalk of T. galarzai ( Fig. 4 ; see also Fig. 3 .C in Giani & Rodriguez, 1988).

Figures

FIGURE 3. Male duct in Troglodrilus species. A: histological section of the male duct in T. jugeti n. sp.; B: dissected male duct in T. galarzai. Abbreviations: ge: granular epithelium, le: light epithelium, p: penis, pr: prostate gland, ps: penial sac, psh: penial sheath, vd: vas deferens. Scale bars: 50 µm.

FIGURE 4. Differences in the penial sheath between T. jugeti n. sp. and T. galarzai. A – B: Montgelas population; C – F: Crotot population; G – I: Santa Eufemia – Ereñozar population; J – M: Gorbeia population. Scale bars: 50 µm. Arrows point to longitudinal folds in the penial sheaths.

FIGURE 5. Spermatheca in Troglodrilus species. A: spermathecal duct in a dissected specimen of T. jugeti n. sp.; B: histological section of the spermathecal duct in T. jugeti n. sp.; C: dissected spermatheca and male duct in T. galarzai; D: bulbous spermathecal duct in a dissected specimen of T. galarzai. Abbreviations: ps: penial sac, psh: penial sheath, sa: spermathecal ampulla, sv: spermathecal vestibule, sd: spermathecal duct. Scale bars: 50 µm.