Mecolaesthus pusillus Huber, 2020

Huber, Bernhard A. & Villarreal, Osvaldo, 2020, On Venezuelan pholcid spiders (Araneae, Pholcidae), European Journal of Taxonomy 718, pp. 1-317 : 133-137

Mecolaesthus pusillus Huber sp. nov.

urn:lsid:zoobank.org:act:884F37CB-9F5F-454E-9A5B-CE94C07741CF

Figs 471–475 , 479–487 , 1044

Diagnosis

Easily distinguished from most known congeners (except M. alegria Huber sp. nov.) by armature of male chelicerae ( Figs 485–486 ; pair of large frontal apophyses set with large modified hairs and pair of simple distal apophyses), by shape of procursus ( Figs 479–481 ; without retrolateral process; tip with pair of dark sclerites connected by transparent membrane), and by epigynum with pair of dark internal structures distinct in uncleared specimens ( Fig. 473 ). From very similar M. alegria Huber sp. nov. by details of male cheliceral armature (large frontal apophyses directed downward rather than forward; simple distal apophyses without accompanying globular hairs), by shape of bifid distal bulbal sclerite ( Figs 482–484 ; dorsal sclerite much narrower in dorsal view), by shape of epigynum ( Fig. 473 ; longer than wide, narrowing posteriorly), and by internal female genitalia ( Figs 474–475 , 487 ; shape of large lateral ear-shaped structures). From most known congeners (except M. alegria Huber sp. nov., M. arepa Huber sp. nov., and M. guasacaca Huber sp. nov.) also distinguished by distinct median process posteriorly on male carapace.

Etymology

The species name (Latin: small) refers to the small size of this species compared to known congeners; adjective.

Type material

VENEZUELA – Aragua • ♂ holotype, ZFMK (Ar 21935), Puerto Colombia (10.5025° N, 67.6057° W), 25 m a.s.l., 2 Dec. 2018 (B.A. Huber, O. Villarreal M.) .

Other material examined

VENEZUELA – Aragua • 1 ♂, 2 ♀♀ (and one female abdomen transferred from pure ethanol), ZFMK (Ar 21936), and 3 ♀♀, 1 juv. in pure ethanol, ZFMK (Ven18-238) (one female abdomen transferred to ZFMK, Ar 21936), same collection data as for holotype • 1 ♀, ZFMK (Ar 21937), and 1 ♀ in pure ethanol, ZFMK (Ven18-240), between Maracay and Puerto Colombia (10.4304° N, 67.5998° W), 380 m a.s.l., 2 Dec. 2018 (B.A. Huber, O. Villarreal M.) • 1 ♂, MIZA 105581 ( MAGS 1546 ), Chuao [10.494° N, 67.527° W], 30 Mar. 2000, collector not known .

Description

Male (holotype)

MEASUREMENTS. Total body length 2.1, carapace width 0.8. Distance PME–PME 80 µm; diameter PME 80 µm; distance PME–ALE 60 µm; diameter AME 20 µm; distance AME–AME 15 µm. Leg 1: 23.5 (5.5 +0.3 +5.8+10.4 + 1.5), tibia 2: 3.6, tibia 3: 2.8, tibia 4: 3.3; tibia 1 L/d: 89.

COLOR (in ethanol). Carapace pale ochre with brown lateral marginal bands and posterior triangular mark, ocular area not darkened, clypeus brown; sternum light brown, laterally with indistinct light marks; legs pale ochre, without dark rings; abdomen pale greenish gray, dorsally and laterally densely covered with dark bluish marks, ventrally with brown mark in gonopore area and bluish median marks in front and behind gonopore; book lung covers light brown; without dark plate above pedicel.

BODY. Habitus as in Fig. 471 . Ocular area slightly raised. Carapace anteriorly with shallow but distinct thoracic groove, posteriorly not inflated but with distinct median process. Clypeus unmodified. Sternum wider than long (0.60/0.40), unmodified. Abdomen slightly elongated, pointed at spinnerets.

CHELICERAE. As in Figs 485–486 , with pair of large frontal apophyses, each provided with two large modified hairs near tip and three large modified hairs proximally, and pair of simple distal apophyses.

PALPS. In general similar to M. niquitanus (González-Sponga, 2011) (cf. Figs 388–389 ); coxa with retrolateral apophysis, trochanter barely modified, femur proximally with large retrolateral-ventral process, dorsally with low hump, distally with ventral conical process (arrow in Fig. 481 ); retrolateral trichobothrium on tibia very distal; procursus ( Figs 479–481 ) at basis with dorsal process with obtuse tip, without retrolateral process, with pair of distal sclerites connected by transparent membrane; genital bulb ( Figs 482–484 ) with large process partly membranous/whitish, with distinctive distal sclerite divided into two lobes.

LEGS. Without spines and curved hairs; few vertical hairs; coxa 4 unmodified; retrolateral trichobothrium of tibia 1 at 3.5%; prolateral trichobothrium present on all leg tibiae; tarsus 1 with ~35 pseudosegments, indistinct.

Female

In general similar to male ( Fig. 472 ), but carapace posteriorly without median process. Tibia 1 in three females: 3.6, 3.9, 4.2. Epigynum ( Fig. 473 ) relatively small dark brown plate, only slightly protruding, anterior margin straight, posteriorly narrowing, with pair of dark internal structures distinct in uncleared specimens; without posterior plate. Internal genitalia ( Figs 474–475 , 487 ) with large lateral ear-shaped structures, pore plates in vertical lateral position.

Distribution

Known from three neighboring localities in the Venezuelan state Aragua (Fig. 1044).

Natural history

In Puerto Colombia, the spiders were found in small webs slightly above the very dry leaf litter of a degraded forest near the town. The locality was shared by only one other pholcid ( Mesabolivar eberhardi Huber, 2000 ). The forest at the second locality (between Maracay and Puerto Colombia) was also disturbed but more humid, and was home to three further pholcid species ( Mesabolivar eberhardi , Metagonia latigo Huber sp. nov., Priscula salmeronica González-Sponga, 1999 ).

One female had a very large whitish genital plug.

Figures

Figs 471–478. Mecolaesthus Simon, 1893; live specimens; epigyna, ventral views and cleared female genitalia, ventral and dorsal views. 471–475. M. pusillus Huber sp. nov.; male from Aragua, Puerto Colombia and female with egg sac from between Maracay and Puerto Colombia; epigynum and cleared female genitalia from Aragua, Puerto Colombia (type locality; ZFMK Ar 21936). 476–478. M. alegria Huber sp. nov.; from Falcón, Santa Cruz de La Alegría (type locality; ZFMK Ar 21938).

Figs 479–487. Mecolaesthus pusillus Huber sp. nov.; from Aragua, Puerto Colombia (type locality; ZFMK Ar 21936). 479–481. Left palpal tarsus and procursus, prolateral, dorsal, and retrolateral views (arrow: ventral femur apophysis). 482–484. Left genital bulb, prolateral, dorsal, and retrolateral views. 485–486. Male chelicerae, frontal and lateral views. 487. Cleared female genitalia, dorsal view. Scale lines: 0.2 mm.

Figs 388–389. Mecolaesthus niquitanus (González-Sponga, 2011); type from Trujillo, Niquitao (MIZA 105788; MAGS 1289); left male pedipalp, prolateral and retrolateral views. Scale line: 0.3 mm.