Gianius navarroi Rodriguez & Achurra, 2010, n. sp.

Gianius navarroi n. sp. (Figures 1–2) Phallodrilinae n. sp. in Camacho et al. 2006. Holotype. MNCN 16.03/3051. An incomplete mature specimen, stained in Ehrlich’s Haematoxylin and whole-mounted in Canada balsam. Type locality. Ojo Guareña cave (site: “Granja Ortiz”, 1 June 2002), northern Burgos, Spain. UTM coordinates for the Palomera entrance: X:446595, Y:4764790, Z:724. Paratypes. MNCN 16.03/3052. A complete mature specimen (unmated) from the type locality, site: “Gour de las Hojas” (8 March 2003). A complete mature specimen in the collection at the University of the Basque Country (UPV/EHU), from the type locality, 11 June 2007. Both specimens are stained in Ehrlich’s Haematoxylin and whole-mounted in Canada balsam. Etymology. Named after the physiologist Dr. Enrique Navarro who has helped P. Rodriguez in sampling numerous sites for the study of aquatic oligochaetes, and has collaborated in applied research with oligochaetes. Description. Length of preserved worms 1.7 mm; number of segments (in two complete specimens) 23 and 26; maximum diameter 150 µm in segment XI. Prostomium rounded, with glandular epidermis (Fig. 1A). Pygidium short and wide (Fig. 1B). Body wall consisting of a fine cuticule (ca 1 µm thick), an epidermal layer (5 µm thick) and a relatively poorly developed musculature (2–3 µm thick). Clitellum formed by glands disposed in one layer, from the last third of segment X back to the beginning of segment XII. There is no secondary annulation. One pair of simple spermathecal pores in the most anterior part of segment X, opening in line with ventral chaetae. One pair of male pores in segment XI on porophores, in line with ventral chaetae. All chaetae bifid, 24–27 µm long, with distal tooth shorter than proximal. Anterior segments with 2–5 chaetae per bundle, 2 in postclitellar segments. Chaetal bundles are in the posterior third of the segment. A bundle of 5 penial chaetae forms an arc, towards the sagittal plane of the body (Fig. 2). Penial chaetae straight, with bent distal end, bifid, and of similar length to somatic chaetae. Gianius navarroi A: anterior part of the body in dorso-ventral view, IV–VII: segment number; B: anterior and posterior ends of the body in lateral view; C: segments VII and VIII. Abbreviations: b: brain, cc: chloragogen cells, i: intestine, od: oesophageal diverticula, ph: pharynx, phg: pharyngeal glands, py: pygidium. Scale bars: A and B: 100 µm, C: 50 µm. Brain with two histologically distinct sections: anterior and posterior parts having large nuclei intensely stained with haematoxylin, and a granulated median part that does not stain well. No coelomocytes observed within the coelomic cavity. Pharyngeal glands in segments III–V, dorsal in III, and both lateral and ventral in segments IV and V (in a paratype, glands also ventrally in VI). Chloragogen cells form a layer on the gut from segment VI backwards. In segment VII, a pair of dorsal digestive diverticula, can occupy half or the entire length of the segment, and appear to be attached to the oesophagus at the posterior end of the segment (Figs. 1A, C). A dilatation of the gut in segment VIII is interpreted as the beginning of the intestine (Figs. 1B, C). One pair testes in segment X and one pair ovaries in segment XI. Sperm sacs in segment XI (in one specimen spermatogonia and spermatocytes are free in the coelom of segment X). Male ducts paired, with two prostate glands: one ental, close to the junction of the vas deferens with atrium; and other ectal, close to the male pore, much smaller than the ental one. A ciliated vas deferens (6 µm diameter) joins the atrium apically. Atria tubular (77 µm long, up to 15 µm diameter) and curved; thicker in the middle in lateral view (with homogeneous diameter in dorsal view) and gradually narrowing to both ental and ectal ends. The atrial musculature is thin (2–3 µm thick) and the lumen is ciliated or filled with granules (as in Fig. 2). The atria open into salient round porophores (ca 10 µm long), where the penial chaetae are located. Female funnels were not observed. One pair of spermathecae, with a stout duct (20 µm long, 13–16 µm wide) and an elongated globular ampulla (40–50 µm long, 16–17 µm maximum diameter), which contains sperm forming a loop. Distribution and habitat. Gianius navarroi n. sp. is known only from Ojo Guareña cave system, and it is likely to be a stygobiont. The species was collected from two different epikarstic sites within the cave, but was rare, at most one specimen per sample. Habitats sampled were puddles and cave streams, having temporary or permanent water, at depths up to 40 cm; sediment was composed of mud, sand and/or stones. Water temperature was 8.4–9.9ºC, pH 7.8–8.0, dissolved oxygen 74.3–78.4 % saturation and conductivity 389–465 µS/cm. Taxonomic remarks. Gianius navarroi n. sp. has spermathecal pores in line with the ventral chaetae, spermathecae with short ducts, vas deferens entering the apical end of an elongated and curved atrium, and two prostate glands per atrium attached to proximal and distal ends, respectively. All of these characteristics are diagnostic for the phallodriline genus Gianius Erséus, 1992. The presence of digestive diverticula in segment VII was previously known only in the species Gianius labouichensis (Rodriguez and Giani, 1989); although the connection of the diverticula with the gut appears to be in the posterior end of the segment for the new species, whereas for G. labouchensis the single diverticulum connects anteriorly. However, the latter is a distinctive species, well distinguished from other congeners by the lack of penial chaetae, a uniformly tubular atrium with a protrusible pseudopenis, and elongated narrow spermathecal ampulla. The general structure of the male duct in G. navarroi n. sp. is more similar to the remaining species of the genus, being closest to G. aquaedulcis (Hrabë, 1960), G. cavealis Juget and des Chatelliers, 2001 and G. anatolicus Arslan, Timm and Erséus, 2007 based on the thin atrial musculature and the moderate (4–5) number of penial chaetae. Gianius cavealis is well distinguished from the new species by its distal atrial duct well separated from an atrial ampulla, and G. anatolicus by the presence of a long, simple spermathecal duct and three different types of somatic chaetae. The general structure of male duct and spermatheca are similar to G. aquaedulcis, and differences are mainly related to the relative size of the prostate glands (both glands large and of about equal size, in G. aquaedulcis but of visibly different size in the new species), as well as the size of chaetae (41 µm in G. aquaedulcis) and the presence of oesophageal digestive diverticula. The G. aquaedulcis material described by Farara and Erséus (1991) in North America has a larger body size and wider atria (33–38 µm width); it is distinguished from the new species by the absence of noticeable porophores at the male pores, (described as “simple male pore on inconspicuous papilla”), and by the blunt ental end of the atria. The shape of the pygidium in G. n a v a r ro i is unusual, but very similar to that described for Mexidrilus obtusus by Erséus (1992: Fig.13). Gianius navarroi n. sp. is separated from the previously known species of the genus by the presence of oesophageal diverticula, salient round porophores with the penial chaetae, and marked difference in size of prostate glands (ental gland larger than distal). Isochaetides gianii n. sp. (Figures 3–5) Lamadrilus sp. in Achurra and Rodriguez (2008) Holotype. MNCN 16.03/3053. A dissected worm, stained in Ehrlich’s Haematoxylin and mounted in Canada balsam. Type locality. Apraiz karstic spring (6 September 2005), Santa Eufemia–Ereñozar karst unit, Biscay, Spain. UTM coordinates X:524225, Y:4801350, Z: 22. Paratypes. USNM 2052660. A dissected specimen from the type locality (6 September 2005). MNCN 16.03/3054: two whole-mounted specimens from Argatxa spring (30 September 2005). In the collection at the University of the Basque Country (UPV/EHU): a sectioned and a dissected specimen from the type locality (6 September 2005); a dissected specimen from Oxiña spring (1 February 1985). All sites in Santa Eufemia– Ereñozar karstic unit, Biscay, Spain. Other material. Three specimens preserved in 70% alcohol from the type locality (6 September 2005). Two dissected and three specimens in 70% alcohol, from Argatxa spring (30 September 2005). Four sectioned, seven dissected, two whole-mounted and 17 specimens preserved in 70% alcohol, from Aulestia spring (23 February 1985). All in the collection at the University of the Basque Country (UPV/EHU). Other localities. Argatxa spring: UTM coordinates X:527790, Y:4800925, Z:2; Oxiña spring: X:529825, Y:4801300, Z:38; Aulestia spring: X: 536494, Y: 4794430, Z:66. All in Santa Eufemia–Ereñozar karst unit. Etymology. Named after Dr. Narcisse Giani for his important contribution to the taxonomy and general biology of aquatic oligochaetes and also for his important role in the formation of many oligochaete taxonomists (including the first author). Description. Body length 8–10 mm; segment number 59–83; mean body diameter 260 µm (range: 180– 335 µm) in segment V, and 324 µm (225–390 µm) in segment VIII. Prostomium rounded or conical, 75–125 µm long, width about the same or wider at its base (all measurements in fixed individuals). Body wall consisting of a thin cuticle (<1 µm), smooth epidermis (5–10 µm thick, but up to 22 µm in the clitellum) and relatively poorly developed musculature (5–7 µm thick). There is no secondary annulation. Clitellum formed by a single layer of glandular cells, extended from anterior part of XI, back to the line of chaetae in segment XII; no glands in the region between the male pores. One pair of deep folds hiding spermathecal apertures (irregular in shape) in segment X, in line with ventral chaetae. One pair of male pores in segment XI, close to and slightly lateral to the ventral chaetae. In some

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