Ariadna motumotirohiva, Giroti & Cotoras & Lazo & Brescovit, 2020

Giroti, André Marsola, Cotoras, Darko D., Lazo, Pedro & Brescovit, Antonio Domingos, 2020, First endemic arachnid from Isla Sala y Gómez (Motu Motiro Hiva), Chile: a new species of tube-dwelling spider (Araneae: Segestriidae), European Journal of Taxonomy 722, pp. 97-105 : 99-102

Ariadna motumotirohiva sp. nov.

urn:lsid:zoobank.org:act:BC432E25-E52D-4E0B-896D-0BDCE97BD2D4 Figs 1–3

Segestriidae sp. – Hershauer et al. 2020: 3, fig. 3b.

Diagnosis

Females of Ariadna motumotirohiva sp. nov. are similar to those of Ariadna perkinsi Simon, 1900 and Ariadna lebronneci Berland, 1933 due to the dark dorsal abdominal pattern ( Fig. 2A ; Giroti & Brescovit 2018: fig. 31a, e), but differ from the former by the anterior receptaculum with the dorsal lobe globous ( Fig. 3 ; Giroti & Brescovit, 2018: fig. 31i–j), by the presence of three promarginal teeth on the chelicerae and femur IV with dorsal macrosetae, and from the latter by four promarginal teeth (see Berland 1933: 44, figs 1–2).

Etymology

The name refers to the name given by the Rapa Nui people to the type locality, 'Motu Motiro Hiva'; noun in apposition.

Type material

Holotype

CHILE • ♀; V Región de Valparaíso, Isla Sala y Gómez ; 26°28′ S, 105°28′ W; Nov. 2012; P. Lazo leg.; MNHN ( MNHN 8366 ).

Paratype

CHILE • ♀; V Región de Valparaíso; same collection data as for holotype; IBSP ( IBSP 246895 ) .

Description

Female (holotype) (measurements in mm)

Carapace orange with cephalic region reddish orange; eyes bounded by dark outlines ( Fig. 2A ). Chelicerae, endites and labium dark reddish orange ( Fig. 2C ). Sternum light orange with darker margins, and four pairs of dark marginal areas ( Fig. 2B ). Palps brownish orange, gradually darkening distally ( Fig. 2B ). Legs brownish orange with pairs I–II darker, and metatarsi and tarsi I–II reddish orange ( Fig. 2 F–G). Abdomen whitish grey, with a fainted dark dorsal pattern comprising arrow-shaped marks ( Fig. 2 A–B). Total length 13.36; carapace 6.4 long, 3.76 wide. Carapace oblong, cephalic region narrower than thoracic region, with short setae conspicuously delimiting it. Six indirect eyes, with the posterior ones in a slightly recurved line ( Fig. 2A ). Chelicerae conical, wider basally, with frontal setae ( Fig. 2A, C ); chelicerae with one retromarginal and three promarginal teeth. Endites spatulate, narrowed medially, rounded distally and proximally. Labium longer than wide, with a narrowed distal region. Labrum well developed, longer than the labium ( Fig. 2C ). Palps short and robust, with one diaxially orientated articulated claw; tarsi and tibia with prolateral setae. Legs robust, pair III directed forward ( Fig. 2 A–B, F–G). Leg formula: I-IV-II-III. Leg measurements: I, femur 4.48, patella 2.2, tibia 4.4, metatarsus 3.32, tarsus 0.72, total 15.12; II, 3.88, 2.08, 4.12, 3.04, 0.64, 13.76; III, 3.28, 1.76, 2.64, 2.52, 0.8, 11.0; IV, 4.32, 2.16, 3.6, 3.2, 0.8, 14.08. Macrosetae: I, femur d0-0-0-0-0-0/1-1-2/1-0, p0-0-0-0-1-2-1/0-1-0; tibia vp1-1-0-1/0-1-1-0-1-1-0, vr1-1-1-0-1-1-0-1-1-1-0, r0-0-1-0-0-0-0-0; metatarsus vp1-1-1-1-0/1-1- 1-1-1-1-1-0/1-0/1-1, vr1-0-1-1-0-1-1-0-1-1-1-1; II, femur d0-0-1-1-1-2-0-2-0, p0-0-0-0-0-1-0-1-0; tibia p0-1-0-1/0-1/0-0-0-0-0-0, vp1-1-1-1-1/0-1-0-1/0-1-0, vr1/2-1-1-0-1-1-0-1-1/0-0/1-1-0, r0-0-0-1/0-1/0- 0-0-0-0; metatarsus vp1-1-1-0/1-1-1-1-1-1-1-1, vr1-0-1-1-0-1-0-1-1-0-1; IV, femur d0-1-1-1-0-1/0-1/0- 0-0-0, r0-0-0-0-0-0-0-1-0-0; metatarsus vr metatarsal comb with 3 macrosetae. Abdomen membranous, longer than wide, uniformly hairy; epigastric genital plate sclerotized; tracheal system dysderoid like, with the tracheal openings positioned near the epigastric furrow ( Fig. 2 A–B, D). Six spinnerets, ALS with three segments, the basal one crossed by a diagonal membranous band; PLS with distal external sclerite equally sclerotized; colulus distinct and pilose ( Fig. 2E ). Internal female genitalia with anterior receptaculum billobulated, dorsal lobe conspicuously longer than the ventral one, with median and ventral projections; glandular ducts plate medianly positioned; interpulmonary fold with the dorsal margin sclerotized, and a median membranous crack; posterior receptaculum membranous, with tubular invaginations ( Fig. 3 ).

Variation

Female (n = 2): total length 10.8–13.36; carapace 5.92–6.4 long, 3.44–3.76 wide; femur I 3.76–4.48.

Note

For comparison we used the female specimen of A. perkinsi described by Giroti & Brescovit (2018) (IBSP 209056) and the original description and illustrations provided by Berland (1933: 44) of A. lebronneci .

Distribution

Only known from the type locality ( Fig. 1 ).

Figures

Fig. 1. Map of southern South America and Isla Sala y Gómez in detail. The islet is located approximately in front of Chañaral along the chilean coast.

Fig. 2. Ariadna motumotirohiva sp. nov., ♀, holotype (MNHN 8366). A. Habitus, dorsal view. B. Habitus, ventral view. C. Endites, labium and labrum, ventral view. D. Epigastric furrow, ventral view. E. Spinnerets, ventral view, arrowheads showing the diagonal membranous stripes of the ALS. F. Right leg I, prolateral view. G. Right leg I, retrolateral view. Scale bars = 1 mm.

Fig. 3. Ariadna motumotirohiva sp. nov., ♀, paratype (IBSP 246895). A–D. Internal genitalia. A, C. Lateral view, arrowhead in A = median membranous crack. B, D. Detail of the anterior receptaculum, ventral view.