Mecolaesthus fallax Huber 2020, sp. nov.
Creators: name: Huber, Bernhard A.
name: Villarreal, Osvaldo
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Pholcidae
Mecolaesthus
Mecolaesthus fallax

description: 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.
description: Published as part of Huber, Bernhard A. & Villarreal, Osvaldo, 2020, On Venezuelan pholcid spiders (Araneae, Pholcidae), pp. 1-317 in European Journal of Taxonomy 718 on pages 157-160, DOI: 10.5852/ejt.2020.718.1101, http://zenodo.org/record/4069574