Mecolaesthus graphorn Huber 2020, sp. nov.

Mecolaesthus graphorn Huber sp. nov.

urn:lsid:zoobank.org:act: 8A390CA7-EF0A-4271-A9B7-FAC11977C0C3

Figs 506–507, 510–522, 545–547, 1046

Diagnosis

Easily distinguished from known congeners by details of male pedipalp (Figs 512–519; procursus slender and simple, with distinct limit between black and transparent sections; genital bulb with complex and distinctive embolar division), by armature of male chelicerae (Figs 520–521; frontal apophyses with pointed tip), by epigynum (Fig. 545; small rectangular anterior plate, no posterior plate), and by internal female genitalia (Figs 522, 547; large oval pore plates connected posteriorly to rounded sclerites).

Etymology

Named for the graphorn, a large, extremely dangerous humpbacked creature which lives in the mountains of Europe; noun in apposition.

Type material

VENEZUELA – Aragua • ♂ holotype, ZFMK (Ar 21943), Henri Pittier National Park, forest near La Cumbre (10.3575° N, 67.5771° W), 1450 m a.s.l., 20 Feb. 2020 (B.A. Huber, O. Villarreal M.).

Other material examined

VENEZUELA – Aragua • 3 ♂♂, 5 ♀♀, ZFMK (Ar 21944), and 2 ♂♂, 3 ♀♀ in pure ethanol, ZFMK (Ven20-160), same collection data as for holotype.

Description

Male (holotype)

MEASUREMENTS. Total body length 3.8, carapace width 1.8. Distance PME–PME 90 µm; diameter PME 140 µm; distance PME–ALE 90 µm; distance AME–AME 15 µm; diameter AME 20 µm. Leg 1: 42.9 (10.2 +0.5+9.9 +18.4 +3.9), tibia 2: 5.8, tibia 3: 4.5, tibia 4: 5.6; tibia 1 L/d: 83.

COLOR (in ethanol). Carapace mostly dark ochre to black, with pair of pale greenish-gray marks behind ocular area, rear side of carapace inflation also pale, with black median line; sternum light, with dark brown lateral marginal bands widening and connected posteriorly; legs ochre to light brown, with indistinct darker rings on femora (subdistally) and tibiae (proximally), tips of femora and tibiae light; abdomen gray, dorsally and laterally with dark bluish marks, ventrally with small ochre mark in gonopore area and dark bluish median band behind gonopore; book lung covers not darkened; abdomen without ventral and dorsal anterior modifications.

BODY. Habitus as in Fig. 506. Ocular area moderately raised. Carapace strongly inflated, with deep thoracic groove. Clypeus unmodified. Sternum wider than long (0.92/0.76 – slightly deformed), unmodified. Abdomen slightly elongated, pointed at spinnerets.

CHELICERAE. As in Figs 520–521, with frontal apophyses with pointed tip; indistinct dark ridge distally between fang joint and lamina.

PALPS. As in Figs 512–513; coxa with retrolateral-ventral apophysis, trochanter barely modified, femur proximally with large retrolateral-ventral process whitish on prolateral side, dorsally with low hump, distally with distinct ventral process; retrolateral trichobothrium on tibia not very distal; tarsus with short trilobed dorsal process; procursus (Figs 514–516) slender and simple, with distinct limit between black and transparent sections; genital bulb (Figs 517–519) with small prolateral-ventral process (arrow in Fig. 517), complex embolar division apparently forming furrow for procursus.

LEGS. Without spines and curved hairs; few vertical hairs; coxa 4 unmodified; retrolateral trichobothrium of tibia 1 at 3%; prolateral trichobothrium present on all leg tibiae; tarsus 1 with ~65 pseudosegments, mostly distinct.

Male (variation)

Tibia 1 in five males (including holotype): 8.5–9.9 (mean 9.4). One male with carapace strongly inflated like in holotype (Fig. 510), three males intermediate, one male with barely inflated carapace (Fig. 511).

Female

Similar to male (Fig. 507) but carapace not inflated, considerably smaller and with shorter legs (tibia 1 in four females: 6.4, 6.8, 6.9, 7.2). Epigynum (Fig. 545) relatively small, flat rectangular plate, without

posterior plate. Internal genitalia (Figs 522, 547) with large oval pore plates connected posteriorly to rounded sclerites.

Distribution

Known from type locality only, in Venezuela, Aragua (Fig. 1046).

Natural history

The spiders were collected in a well-preserved humid forest near a small stream. The weakly domed sheet webs had a diameter of ~ 30 cm and were built in sheltered spaces provided by rocks or logs. At disturbance the spiders started to swing/vibrate.