NERUDIA CENTAURA HUBER SP. NOV.

(FIGS 1C, D, 15–18)

Z o o b a n k r e g i s t r a t i o n: u r n: l s i d: z o o b a n k. org:act: 124FC4AB-B97D-445C-AD11-C3604843AED3.

Diagnosis: Easily distinguished from known congeners by dark coloration of prosoma (Fig. 1C, D), by shape of procursus (Fig. 16A–C; dorsal hump at basis, strongly bent towards dorsal, pointed tip), by bulbal processes (Fig. 16D–F; strong pointed ventral apophysis; embolus slightly shorter, with strong dorsal sclerite), by male chelicerae (Fig. 16G, H; strong frontal apophyses with flattened tips; stridulatory files on strong lateral protrusion), and by epigynum and female internal genitalia (Figs 16I, 17; epigynal plate with large, whitish posterior indentation angular anteriorly; internal genitalia with indistinct posterior ‘receptacle’ and unique anterior tubular membranous structure).

Type material: ARGENTINA – Catamarca: • ♂ holotype; ~ 20 km E Paso de San Francisco, ‘site 1’; 26.9276° S, 68.0709° W; 4180 m a.s.l.; 27 Mar. 2019; B. A. Huber and M. A. Izquierdo leg.; LABRE-Ar 587 • 1 ♂, 2 ♀♀, paratypes; same data as holotype; ZFMK Ar 23890 .

Other material examined: ARGENTINA – Catamarca: • 6 ♀♀, 3 juvs, in pure ethanol; same data as holotype; ZFMK Arg215 • 4 ♂♂, 6 ♀♀; same data as holotype; LABRE-Ar 526 • 3 ♀♀, 7 juvs, in pure ethanol; same data as holotype; LABRE-Ar 542 • 3 ♂♂, 5 ♀♀ (one male and two females used for µ-CT study); ~ 20 km E Paso de San Francisco, ‘site 2’; 26.936° S, 68.090–68.095° W; 4270– 4400 m a.s.l.; 27 Mar. 2019; B. A. Huber and M. A. Izquierdo leg.; ZFMK Ar 23891 • 6 ♀♀, 2 juvs, in pure ethanol (one female used for SEM; three female prosomata used for molecular study); same data as preceding; ZFMK Arg216 • 4 ♂♂, 1 ♀; same data as preceding; LABRE-Ar 527 • 6 ♀♀, 3 juvs, in pure ethanol; same data as preceding; LABRE-Ar 551 • 1 ♀; same data as preceding but 4450 m a.s.l.; ZFMK Ar 23892 .

Etymology: The species epithet centaura (Spanish for ‘female centaur’) is taken from Pablo Neruda’s poem ‘Soneto 22’; noun in apposition.

Description

Male (holotype). Measurements: Total body length 1.9, carapace width 0.77. Distance PME–PME 90 µm; diameter PME 55 µm; distance PME–ALE 30 µm; distance AME–AME 20 µm; diameter AME 40 µm. Leg 1: 4.55 (1.25 + 0.25 + 1.30 + 1.30 + 0.45), tibia 2: 1.10, tibia 3: 1.00, tibia 4: 1.38; tibia 1 L/d: 14.

Colour (in ethanol): Prosoma and legs ochre to light brown; legs without dark rings; abdomen monochromous pale grey.

Body: Habitus as in Figure 1C. Ocular area barely raised. Carapace without thoracic groove. Clypeus unmodified. Sternum wider than long (0.56/0.48), without anterior processes. Abdomen globular.

Chelicerae: As in Figure 16G, H; pair of frontal apophyses directed downwards, with obtuse tip slightly flattened; stridulatory files on pair of distinct lateral protrusions.

Palps: As in Figure 15; coxa unmodified; trochanter with indistinct ventral projection; femur cylindrical, only slightly widened distally, proximally with indistinct retrolateral hump and prolateral stridulatory pick (modified hair); patella short; tibia globular; procursus (Fig. 16A–C) simple, in lateral view bent towards dorsal, in dorsal view bent towards prolateral, with pointed tip; genital bulb (Fig. 16D–F) large, with strong pointed ventral apophysis, embolus partly membranous, dorsally with distinct sclerite.

Legs: Without spines and curved hairs; vertical hairs in high densities on tibiae 1–2; retrolateral t r i c h o b o t h r i u m o f t i b i a 1 a t 6 8%; p r o l a t e r a l trichobothrium absent on tibia 1; tarsus 1 with six to seven pseudosegments, distally distinct.

Variation (male): Tibia 1 in 12 males (including holotype): 1.15–1.33 (mean 1.26).

Female: In general, similar to male (Fig. 1D) but with usual low density of vertical hairs on tibiae. Tibia 1 in 22 females: 1.07–1.48 (mean 1.28). Epigynum (Fig. 17A) anterior plate weakly protruding, with large, whitish posterior indentation; posterior plate large, simple. Internal genitalia (Figs 16I, 17B–E) with simple ‘receptacle’ (Fig. 17C) and unique tubular membranous structure in anterior position (possibly opening towards the outside, not towards the uterus externus).

Distribution: Known from two neighbouring localities in Argentina, Catamarca (Fig. 3).

Naturalhistory: Bothlocalitiesweresimilar, dominated by rocks and grasses [possibly Calamagrostis crispa (Rúgolo & Villav.) Govaerts; Julieta Carilla, pers. comm. August 2020] (Fig. 45C). The precipitation in this area is low (~ 150 mm mean annual precipitation) and largely limited to three months per year (~70% in December–February) (https://www.meteoblue.com/). We visited the locality at the end of the ‘humid’ season, in March, and often found humid patches of soil under large rocks, with considerable numbers of small, whitish collembolans. At the lower site (4180 m a.s.l.), this microhabitat seemed to contain little else than one species each of collembolans, pholcids, linyphiids and ants. At the higher site (4270–4450 m a.s.l.), the diversity seemed to be slightly higher, including, in addition, a species each of theridiids, filistatids and neopteran insects. At both localities, the pholcids were found sitting on the undersides of the rocks. They did not move and were thus easy to catch. Of the 36 females seen, only one had an egg-sac.

Precise climate data do not exist for these localities, but simulations of meteorological models (https://www. meteoblue.com/) suggest that temperatures fall below 0 °C almost every night of the year, with daily minima below –10 °C for seven months (April–October). In 2019, the temperatures repeatedly dropped below –20 °C in this period.