Mecolaesthus graphorn Huber

Huber, Bernhard A. & Villarreal, Osvaldo, 2020, On Venezuelan pholcid spiders (Araneae, Pholcidae), European Journal of Taxonomy 718, pp. 1-317: 143-145

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Mecolaesthus graphorn Huber

sp. nov.

Mecolaesthus graphorn Huber   sp. nov.

Figs 506–507 View Figs 506–509 , 510–522 View Figs 510–513 View Figs 514–522 , 545–547 View Figs 545–553 , 1046


Easily distinguished from known congeners by details of male pedipalp ( Figs 512–519 View Figs 510–513 View Figs 514–522 ; 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 View Figs 514–522 ; frontal apophyses with pointed tip), by epigynum ( Fig. 545 View Figs 545–553 ; small rectangular anterior plate, no posterior plate), and by internal female genitalia ( Figs 522 View Figs 514–522 , 547 View Figs 545–553 ; large oval pore plates connected posteriorly to rounded sclerites).


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.) GoogleMaps   .

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 GoogleMaps   .


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 View Figs 506–509 . 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 View Figs 514–522 , with frontal apophyses with pointed tip; indistinct dark ridge distally between fang joint and lamina.

PALPS. As in Figs 512–513 View Figs 510–513 ; 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 View Figs 514–522 ) slender and simple, with distinct limit between black and transparent sections; genital bulb ( Figs 517–519 View Figs 514–522 ) with small prolateral-ventral process (arrow in Fig. 517 View Figs 514–522 ), 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 View Figs 510–513 ), three males intermediate, one male with barely inflated carapace ( Fig. 511 View Figs 510–513 ).


Similar to male ( Fig. 507 View Figs 506–509 ) 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 View Figs 545–553 ) relatively small, flat rectangular plate, without

posterior plate. Internal genitalia ( Figs 522 View Figs 514–522 , 547 View Figs 545–553 ) with large oval pore plates connected posteriorly to rounded sclerites.


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.


Germany, Bonn, Zoologische Forschungsinstitut und Museum "Alexander Koenig"


Zoologisches Forschungsmuseum Alexander Koenig