Saccarella, Schönhofer Jochen Martens, 2012

Schönhofer Jochen Martens, Axel L., 2012, The enigmatic Alpine opilionid Saccarella schilleri gen. n., sp. n. (Arachnida: Nemastomatidae) - isolated systematic placement inferred from comparative genital morphology, Organisms Diversity & Evolution (New York, N. Y.) 12 (4), pp. 409-419 : 412-414

Saccarella gen. n.

Diagnosis: A new genus delineated by male genital morphology (dorsal and ventral lateral folds in distal part of truncus penis), truncus and glans straight, not bent (from dorsal/ventral view), weak glans armament (inconspicuous minute bristles), male cheliceral apophysis (large in terms of nemastomatid morphology, extended medial secretion field of minute pores), armament of dorsal side of scute (without noticeable single thorns, spines or rows of thorns); leg morphology (femur to tibia of leg I markedly inflated, short in terms of nemastomatid morphology); coloration (black, without silvery spots on dorsal scute). Presently one species known.

Type species: Saccarella schilleri sp. n. (by monotypy and original designation).

Derivatio nominis: The name is derived from Monte Saccarello at the western edge of the Italian Ligurian Alps; gender is female.

Saccarella schilleri sp. n.; Figs. 11–27.

The new species is described under the biological species concept ( Mayr 1942 and exemplified for Opiliones by Martens 1969) based on unique morphological characters suggesting reproductive isolation.

Holotype: m#, Italy, Liguria, Prov. Imperia, Monte Saccarello, close to village Monesi di Triora , N: 44.071° E: 7.749°; 1,475 m, W. Schiller leg. 30.05.1986 (CJM 7006; ex CJM 3112).

Paratypes: 6 m #, 1f#, same data as holotype (CJM 3112) .

Distribution: The species has been collected in the Italian South-western Alps, a hotspot of alpine arthropod biodiversity and endemism ( Isaia et al. 2011; Vigna Taglianti et al. 1999). Despite several attempts to relocate the species also in the frame work of the EDIT project (see Acknowledgments), it remains known only from one narrowly circumscribed locality.

Diagnosis: Saccarella schilleri sp. n. differs from all Nemastomatidae by its contrasting genital morphology, with folds alongside the distal truncus and a blunt stylus, otherwise refer to genus diagnosis. While close relatives of Saccarella schilleri sp. n. are not discernible, it is discriminate from other syntopic nemastomatids. To aid determination: Centetostoma centetes ( Simon, 1881) is much smaller, Histricostoma dentipalpe slightly larger, and both exhibit elongated spines on the dorsal opisthosoma, whereas Nemastoma dentigerum is of the same size and coloration and not discernible in the field. Males of Saccarella schilleri sp. n. lack the palpal apophyses present in males of Nemastoma dentigerum . The shape of the cheliceral apophyses in Nemastoma dentigerum , Centetostoma centetes and Saccarella schilleri sp. n. is superficially similar.

Derivatio nominis: The species’ epithet honours Wolfgang Schiller (Grenzach-Whylen, Germany), a distinguished specialist of carabid Coleoptera and sophisticated collector of soil arthropods, who provided the only series of this unexpected species.

Description: Measurements Leg II (holotype m#, f# in parentheses): Femur 1.2 (1.1), Patella 0.4 (0.4), Tibia 1.0 (0.9), Metatarsus 1.5 (1.4), Tarsus 1.4 (1.3). Length of dorsal scute: 1.4–1.6 (1.6).

Figs. 11–15 Saccarella schilleri gen. n. sp. n., 11:

lateral view; 12–15: dorsal view; 11, 13–15: males; 12:

female; 11-14: paratypes; 15:

holotype; 13: individual of pic-

ture 11 and 14, cleaned from soil and secretion; 15: freshly moulted and untreated specimen. Bars all 1 mm, in 11 for

11–12, 15; in 14 for 13–14

Body (Figs. 11–15) Coloration: body and legs deep black several weeks after final moult, without silvery or golden markings. A thin layer of agglutinated secretion covers the dorsal scute; thus older specimens appear with a greyish to whitish dorsum after fixation in alcohol (Figs. 11–12, 14, removed in 13); in males the area of secretion is restricted to prosoma and opisthosomal areae I and II (Figs. 11–12), in the female extended to area III (Fig. 12).

Dorsal side: All scutal areae and free tergites covered densely with fine acute granules, spaced about their own size, largest near frontal end of scute close to tuber oculorum, on areae I–V of the dorsal scute one pair each of larger and markedly higher tubercles, their inter-distances enlarging towards the rear areae (Fig. 15), free tergites I–III with a row of slightly more pronounced granules at rear end.

Tuber oculorum (Figs. 11–15): slightly elevated, rising from frontal margin of scute, height about two-thirds of length, as long as wide, irregularly covered with tubercles, increasing in size from posterior to anterior margin; eyes prominent, their diameter about half the size of the height of the tuber. Supracheliceral lamellae consisting of four small sclerite plates, with distally pointing mushroom- to ambos-shaped tubercles.

Ventral side: genital operculum and free sternites with scattered small tubercles, inconspicuous on the sternites and on corona analis; coxae pro- and retro-laterally with a scattered row of 6–12 blunt or ambos-shaped tubercles each.

Chelicerae (Figs. 25–27): Males with a large dorso-distal apophysis on basal cheliceral segment, laterally compressed forming a flat, irregularly spoon-shaped form (medial and lateral views); apophysis slightly inclined distally, longer than wide at basis, broadening distally (medial and lateral views), dorsally slightly rounded (medial and lateral views), anterior edge higher than posterior one (medial and lateral view), medial part of apophysis slightly concave, entirely covered with an extrusion area of minute pores for secretion produced in the cheliceral gland; pore area interspersed with medium-sized, more slender hairs.

Pedipalp (Fig. 23): Moderately compact; femur slightly enlarged towards distal end, patella ventrally slightly thickened. Femur to tarsus covered with sparse (femur) to denser (patella, tibia, tarsus) array of bristles, most of them of the clavate glandular type; in both sexes no patella spur armament.

Legs (Figs. 11–12, 14–15, 24): Short and stout in terms of nemastomatid morphology. Femur, patella and tibia of leg I and III markedly inflated, leg IV most slender; femur to tibia partly covered by two types of distinct microstructures (Fig. 24): (1) rounded tubercles, as high as broad, spaced about their diameter and irregularly scattered; (2) considerably smaller scales in the inter-distances; trochanter with tubercles dorsally, on femur throughout; on patella and tibia tubercles restricted to dorsal side, otherwise segments densely covered with scales, causing a finer and more regular appearance; metatarsus and tarsus without granules and scales but densely and regularly covered with short hairs on small tubercles; few longer hairs interspersed. Pseudoarticulations of femora: I–IV (all m#, f# in parentheses): I 0 (0), II 1–2 (2), III 1 (legs missing), IV 2–3 (2–3). In femora IV, number always differs on left and right femur.

Male genital morphology (Figs. 16–22): Penis straight, extremely slender (dorsal/ventral/lateral view), nearly parallel-sided (dorsal and ventral view), slightly and gradually widening toward distal end, in lateral view slightly curved. Glans symmetrical, in straight prolongation of truncus. Broadened truncus base deeply split into two elongated, muscle-bearing portions (Figs. 19–20). Ventral side of truncus (Fig. 17) sub-distally forming a slightly widened wing-like structure, markedly tapering toward basis of glans. Dorsal side of truncus slightly constricted forming a narrow connection, bridging sub-distal part of truncus and basis of glans (Fig. 16); at both lateral sides below the connection the truncus is slightly excavated forming a shallow furrow (Figs. 16, 18, 22); truncus wing slightly longer than glans (Figs. 16–17, 19–20). Armament of glans and stylus sparse, consisting of few minute bristles mainly on lateral and ventral side, glans tapering into short stylus, opening of sperm duct at distal end.