Mecolaesthus fallax Huber, 2020

Huber, Bernhard A. & Villarreal, Osvaldo, 2020, On Venezuelan pholcid spiders (Araneae, Pholcidae), European Journal of Taxonomy 718, pp. 1-317 : 157-160

Mecolaesthus fallax Huber sp. nov.

urn:lsid:zoobank.org:act:D41821FC-0FBA-4028-8543-6F1FFB8B826F

Figs 556–559 , 569–575 , 579–581 , 1045

Mecolaesthus Ven 02/80-12 – Eberle et al. 2018 (molecular data). — Huber et al. 2018: fig. 5.

Diagnosis

Easily distinguished from similar pale six-eyed pholcids ( Systenita prasina Simon, 1893 ; Metagonia spp.) by distinctive pair of apophyses distally on genital bulb ( Figs 569, 571 ), by shape of simple procursus with bifid tip ( Figs 573–574 ), by armature of male chelicerae ( Fig. 572 ; pair of distal lateral apophyses), and by epigynum and female internal genitalia ( Figs 575 , 579–581 ; pair of sclerotized lateral pockets; brown posterior plate; oval median receptacle).

Etymology

The species name (Latin: misleading, deceiving) refers to the intriguing superficial similarity of this species with Systenita prasina ; adjective.

Type material

VENEZUELA – Trujillo • ♂ holotype, ZFMK (Ar 21951), near Boconó , Laguna Negra (9.3054° N, 70.1752° W), 1870 m a.s.l., 21 Nov. 2018 (B.A. Huber, O. Villarreal M.) .

Other material examined

VENEZUELA – Trujillo • 11 ♂♂, 6 ♀♀, 1 juv., ZFMK (Ar 21952–53), and 4 ♀♀, 2 juvs in pure ethanol, ZFMK (Ven18-211), same collection data as for holotype • 1 ♂, MIZA 105578 ( MAGS 1415 ), same locality, 13 Sep. 1996 (A.R. Delgado, J.A. González D., M.A. González S.) • 2 ♂♂, 1 ♀, 1 juv., ZFMK (Ar 21954), and 2 juvs in pure ethanol, ZFMK (Ven18-217), between Boconó and Burbusay (9.3945° N, 70.2674° W), 1820 m a.s.l., 22 Nov. 2018 (B.A. Huber, O. Villarreal M.). – Mérida • 13 ♂♂, 12 ♀♀, ZFMK (Ar 21955–56), and 1 ♀, 1 juv. in pure ethanol, ZFMK (Ven18-221), Mucuy , along Laguna El Suero trail (between 8.629° N, 71.039° W and 8.623° N, 71.034° W), 2270–2690 m a.s.l., 24 Nov. 2018 (B.A. Huber, O. Villarreal M.) • 4 ♂♂, 4 ♀♀, ZFMK (Ar 21957), and 1 ♂, 1 ♀ in pure ethanol, ZFMK (Ven18-233), Monte Zerpa , forest above La Hechicera (8.634° N, 71.163° W – 8.639° N, 71.167° W), 2050–2180 m a.s.l., 26 Nov. 2018 (B.A. Huber, O. Villarreal M., N.A. Sánchez G.) • 4 ♂♂, 3 ♀♀, ZFMK (Ar 21958), and 1 ♂, 2 ♀♀, 5 juvs in pure ethanol, ZFMK (Ven20-112), forest near La Carbonera (8.6276° N, 71.3688° W), 2380 m a.s.l., 8 Feb. 2020 (B.A. Huber, O. Villarreal M., Q. Arias C.) • 1 ♂, ZFMK (Ar 21959), Chorrera Las González (8.5860° N, 71.2989° W), 1750 m a.s.l., 8 Feb. 2020 (B.A. Huber, O. Villarreal M., Q. Arias C.). – Lara • 10 ♂♂, 6 ♀♀, 3 juvs, ZFMK (Ar 21960), and 1 ♂, 3 ♀♀, 7 juvs in pure ethanol, ZFMK (Ven02/100-61), Yacambú National Park , Sendero Ecológico (9.708° N, 69.583° W), ~ 1550 m a.s.l., 15–16 Dec. 2002 (B.A. Huber, A. Pérez González, O. Villarreal M., B. Striffler, A. Giupponi) .

Description

Male (holotype)

MEASUREMENTS. Total body length 2.9, carapace width 0.85. Distance PME–PME 130 µm; diameter PME 70 µm; distance PME–ALE 50 µm; AME absent. Leg 1: 34.1 (8.2 +0.4 +7.9+15.5 + 2.1), tibia 2: 5.1, tibia 3: 3.5, tibia 4: 4.3; tibia 1 L/d: 99.

COLOR (in ethanol). Carapace and ocular area whitish, clypeus dark brown, sternum whitish; legs pale ochre-yellow with slightly darker rings on patella, subdistally on tibia, and at tibia-metatarsus joint; abdomen greenish-gray, with large brown mark in gonopore area.

BODY. Habitus as in Figs 556–557 . Ocular area barely raised. Carapace not inflated posteriorly, with shallow but distinct thoracic groove. Clypeus unmodified. Sternum wider than long (0.65/0.50), unmodified. Abdomen elongate, pointed at spinnerets.

CHELICERAE. As in Fig. 572 , with pair of strong distal lateral apophyses.

PALPS. As in Figs 569–570 ; coxa with retrolateral apophysis, trochanter slightly protruding ventrally, femur proximally with retrolateral apophysis and small ventral projection, distally strongly widened, with large ventral process; procursus ( Figs 573–574 ) simple, with strongly sclerotized dorsal pointed tip and flat ventral triangular process; genital bulb ( Figs 569, 571 ) distally with weakly sclerotized dorsal process (presumably carrying the sperm duct) and distinctive ventral process with two sclerotized apophyses.

LEGS. Without spines and curved hairs; few vertical hairs; retrolateral trichobothrium of tibia 1 at 3%; prolateral trichobothrium present on all leg tibiae; tarsus 1 with ~35 pseudosegments, distally distinct.

Male (variation)

Tibia 1 in 31 other males: 6.7–8.4 (mean 7.7); abdomen color variable, from pale gray to greenish and bluish; some males with wide, bluish or purple median band behind brown mark in gonopore area.

Female

In general similar to male ( Figs 558–559 ), clypeus mark lighter and medially divided. Tibia 1 in 21 females: 5.0–6.1 (mean 5.6). Epigynum ( Fig. 579 ) weakly sclerotized and weakly bulging, internal structures partly visible in uncleared specimens; with pair of dark brown lateral pockets (distance ~ 360 µm); posterior plate large and dark brown. Internal genitalia ( Figs 575 , 580–581 ) with strongly curved median arc, anteriorly with oval median receptacle and pair of lateral V-shaped membranous structures; pore plates contiguous to median arc.

Distribution

Known from several localities in the Andean Venezuelan states Trujillo, Mérida, and Lara (Fig. 1045).

Natural history

In the field, this species is indistinguishable from Systenita prasina : apart from having the same size and habitus, it builds the same weakly domed webs attached at their apex to the undersides of leaves and has the same partly inverted resting position (abdomen dorsal side upwards). At most sampling sites, this was a relatively abundant species. However, the distribution was sometimes patchy; for example, most specimens in the forest near La Carbonera were collected within a few meters.

Figures

Figs 554–559. Mecolaesthus Simon, 1893; live specimens. 554–555. M. yerbatero Huber sp. nov.; male and female from Mérida, between Mérida and Barinas. 556–559. M. fallax Huber sp. nov.; males from Mérida, Mucuy and females from Trujillo, Laguna Negra.

Figs 569–575. Mecolaesthus fallax Huber sp. nov.; from Trujillo, Laguna Negra (type locality; ZFMK Ar 21952–53). 569–570. Left male pedipalp, prolateral and retrolateral (slightly dorsal) views. 571. Left genital bulb, dorsal view. 572. Male ocular area, clypeus, and chelicerae, frontal view. 573. Left palpal segments, retrolateral view. 574. Left procursus, dorsal view. 575. Cleared female genitalia, dorsal view. Scale lines: 0.3 mm (all palpal elements at same scale).

Figs 576–581. Mecolaesthus Simon, 1893; epigyna, ventral views and cleared female genitalia, ventral and dorsal views. 576–578. M. yerbatero Huber sp. nov.; from Mérida, between Mérida and Barinas (type locality; ZFMK Ar 21950). 579–581. M. fallax Huber sp. nov.; from Trujillo, Laguna Negra (type locality; ZFMK Ar 21953).