Ariadna thylacinus Marsh & Stevens & Framenau 2022, sp. nov.
Creators: name: Marsh, Jessica R.
name: Stevens, Mark I.
name: Framenau, Volker W.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Segestriidae
Ariadna
Ariadna thylacinus

description: Ariadna thylacinus sp. nov.
Figs 34a–h, 35a–c, 36a–h, 33
http://zoobank.org/NomenclaturalActs/35549e43-5f97-4724-a240-9aef8954143c
Type material. Holotype ♂. AUSTRALIA: Tasmania: Flat Rock, 42.99°S; 147.95°E, coll. R. Raven, Bush Blitz expedition, 2010 (TMAG J5352).
Paratype ♀: same as holotype (TMAG J5353).
Other material examined. Tasmania: 1 ♂, same as holotype (TMAG J4154).
Etymology. The specific epithet is a noun in apposition and refers to the similarity of the transverse striations on the abdomen of this species to those of the Tasmanian tiger, Thylacinus cynocephalus (Harris, 1808). It is hopefully not a predictor of the species’ future conservation status.
Diagnosis. Ariadna thylacinus sp. nov. is closest to A. alta sp. nov., A. amabilia sp. nov. and A. segmentata. It can be separated from A. segmentata by the male palp having a squared bulb, with a prominent rounded ventral projection which the embolus arises, and by the embolus arising from the dorso-central portion of the bulb (Fig. 35a, b cf. Figs 9a–c, 27a–c). It is differentiated from A. alta sp. nov. by the lack of dual row of macrosetae proventrally on tibia I of females (Fig. 36f, g cf. Fig. 6f, g). It can be differentiated from A. amabilia sp. nov. by the oblong-square pedipalp bulb and the sinuous shape of the apical section of the embolus of A. thylacinus sp. nov., compared to the square bulb of A. amabilia sp. nov. and the smooth curve of the embolus apically (Fig. 35a–c cf. Fig. 9a–c). Ariadna tigrina sp. nov. is from the same type locality as A. thylacinus sp. nov., the two species can be differentiated by the shape of the pedipalp bulb, which is pyramidal in A. tigrina sp. nov., but rounded oblong in A. thylacinus sp. nov.; by the shape of the embolus, which is fine, smoothly curved and hooked apically in A. tigrina sp. nov., but is sinuous apically in A. thylacinus sp. nov. and by the pedipalp tibia, which is inflated in A. thylacinus sp. nov. (Fig. 35a–c cf. Fig. 38a–c).
Description. ♂ (based on holotype TMAG J5352). Total length 8.5.
Colour in ethanol: Carapace dark, reddish brown, becoming darker anteriorly, with raised caput area lighter red brown, bordered by darker red brown; sternum orange brown, maxillae orange brown, paler in colour apically, chelicerae reddish brown; abdomen dorsally pale cream, with nine dark grey, clearly defined chevrons, extended and joined medially, ventrally cream with dark patches centrally and laterally. Legs uniform golden brown. Figs 34a–h.
Cephalothorax: 4.6 long, 3.1 wide, 2.5 high. Carapace oval, narrowing anteriorly, fovea a shallow indented pit, scattered sparse, dark setae, denser anteriorly (Fig. 34a); caput raised towards anterior, highest just behind posterior eye row (Fig. 34c). Labium narrowed anteriorly, about ¾ length of maxillae; chelicerae semi porrect with basal transverse ridge, retromargin with single tooth, promargin with three teeth; sternum elongated oval with precoxal triangles and with smaller, rounded intercoxal extensions, with sparse black setae (Fig. 34b). Eye group 1.0 wide, 0.6 of anterior carapace width; posterior eye row straight, eye group occupying about a half of carapace width (Fig. 34d).
Abdomen: 3.9 long; oval and tapering in shape, covered in sparse setae (Fig. 34a).
Legs: Leg ratio: I>II>IV>III. Leg I femur 4.0, patella 1.3, tibia 3.7, metatarsus 3.7, tarsus 1.4. Leg II femur 4.0, patella 1.3, tibia 3.9, metatarsus 3.4, tarsus 1.3. Leg III femur 2.9, patella 1.3, tibia 2.1, metatarsus 2.0, tarsus 1.0. Leg IV femur 3.7, patella 1.2, tibia 2.8, metatarsus 1.5, tarsus 0.6. Covered in brown setae. Femur I bowed in dorsal view. Macrosetae: Leg I: Femur d2/1ap-dp2ap; tibia p1-2-1-2-1-2-2-1ap, v1-1-1-1-1-1-1ap, r1-1-1-1-1-1; metatarsus p1-1-1-1broken, r1-1-1-1-1ap. Leg II macrosetae femur d1-1/0-dp2ap; tibia p1-1-2-2, v1-1-1-1-1-1, r1-1-1- 1-1-2-1ap; metatarsus p2-1-2-1ap, v1-1ap, r1-1-1-1-1ap. Leg IV femur d1-1-1-dp1ap; tibia p1-1-1-1ap, r2-2-1ap; metatarsus p1, r2-1-2-1ap. Retrolateral distal preening comb with nine macrosetae (Fig. 34e). STC I, II with seven teeth, ITC with small tooth. Tarsi with distal ventral scopulose setae.
Pedipalp: tibia short, about 1 ¼ the length of the cymbium and with a ventral median indention; cymbium rounded square shape, with anterior prolateral extension. Bulb squared-pyramidal in lateral view, embolus long, curved and sinuous apically (Fig. 35a–c).
Description. ♀ (based on paratype, TMAG J5353). Total length 13.7.
Colour in ethanol: Carapace dark, reddish brown, darker around edges with sparse scattered setae, denser towards lateral edges and anteriorly. There is a pale area centrally demarking the raised caput, beginning anteriorly of fovea and bordered by darker red brown, with a darkened median line extending from fovea to half distance between fovea and eye group. Sternum red-brown, paler centrally, with moderately long, scattered dark setae. Labium darker brown, paler apically; maxillae orange brown, paler apically; chelicerae dark brown with dense, long, black setae. Abdomen with metallic sheen, dorsally grey, with faint paler, not well-defined chevrons; ventrally uniform grey. Legs red brown, covered with setae. Figs 36a–h.
Cephalothorax: 5.5 long,3.2 wide, 2.0 high. Carapace rounded rectangular, with broad, square ‘neck’ anteriorly, anterior edge convex, posteriorly with defined median indent, fovea a shallow slit (Fig. 36a); lateral profile domed, highest point at fovea (Fig. 36c). Labium narrowed anteriorly, about ¾ length of maxillae; chelicerae broad, robust with basal transverse ridge, retromargin with single tooth, promargin with three teeth; sternum elongated oval with defined precoxal triangles and with rounded triangular intercoxal extensions (Fig. 36b). Eye group 1.0 wide, 0.5 of anterior carapace width; posterior eye row slightly recurved, eyes small, three pairs of eyes widely separated, eye group occupying about 1/3 of carapace width (Fig. 36d).
Abdomen: 8.2 long. Covered in fine dense setae (Fig. 36a).
Legs: Leg ratio I>II>IV>III. Leg I femur 3.8, patella 1.4, tibia 2.8, metatarsus 2.4, tarsus 1.2. Leg II femur 3.9, patella 1.6, tibia 2.9, metatarsus 1.9, tarsus 0.9. Leg III femur 2.8, patella 1.1, tibia 2.1, metatarsus 1.7, tarsus 0.9. Leg IV femur 3.5, patella 1.1, tibia 2.3, metatarsus 2.2, tarsus 0.9. Femur I bowed in dorsal view. Macrosetae: Leg I femur dp2ap; tibia pv1, v2-2-2, pv1, rv1, v2, pv1, v2ap; metatarsus pv1-1-1, v2-2-2-2-2-1-2ap, rv1. Leg II femur dp1ap; tibia: p1-2, pv1ap, rv1-1-1-1-1ap; metatarsus: 2-2-1-2-1-2-1-2ap. Leg IV femur d1-1; tibia p1ap, v1-1/0; metatarsus rv1-1-1-1ap. Retrolateral distal preening comb with 9 macrosetae (Fig. 36e), with two long macrosetae adjacent. STC I, II with 9 teeth, ITC with small tooth. Tarsi with distal ventral scopulose setae.
Pedipalp: With single, toothless claw, dense clusters of proventral macrosetae on tarsus and tibia; with dense scopulose setae on tarsus.
Genitalia: Despite the female appearing mature externally, with a sclerotised epigynal mound (Fig. 36b), upon dissection the anterior receptaculum was very small and underdeveloped. This may be because the female was subadult, or had a physical deformity
Variation. Specimens examined were consistent in the colour and form of transverse abdominal markings and showed little variation in size.
Distribution. Known only from the type locality, Flat Rock, southeastern Tasmania (Fig. 33).
description: Published as part of Marsh, Jessica R., Stevens, Mark I. & Framenau, Volker W., 2022, A taxonomic revision of the tube-web spiders of the genus Ariadna (Araneae: Segestriidae) in Tasmania, pp. 151-201 in Zootaxa 5105 (2) on pages 189-194, DOI: 10.11646/zootaxa.5105.2.1, http://zenodo.org/record/6332569