Mesabolivar borgesi,

Huber, Bernhard A., 2018, The South American spider genera Mesabolivar and Carapoia (Araneae, Pholcidae): new species and a framework for redrawing generic limits, Zootaxa 4395 (1), pp. 1-178: 123-125

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Mesabolivar borgesi

sp. n.

Mesabolivar borgesi  sp. n.

Figs 545–551View FIGURES 545–551

Mesabolivar  “ MACN 197”: Huber 2014: 139.

Diagnosis. Easily distinguished from known congeners by tip of procursus (strongly S-shaped; Fig. 546View FIGURES 545–551), by armature of male chelicerae (three pairs of frontal apophyses; Figs 547–548View FIGURES 545–551), and shape of epigynum (posterior margin trilobed, without pocket; Fig. 549View FIGURES 545–551).

Etymology. Named for Argentine writer Jose Luis Borges (1899–1986).

Type material. ARGENTINA: Buenos Aires: ♂ holotype, MACN ( Ar 38625)  , 2♂ paratypes, MACN (Ar 20003), Vuelta de Obligado, Caverna La Salamanca [33°35.4’S, 59°49.2’W, 5 m], 29.vii.1972 (C. Cesar)GoogleMaps  .

Other material examined. ARGENTINA: Buenos Aires: 1♂, MACN (20065), Vuelta da Rocha [34°38.4’S, 58°21.8’W, 15 m] xii.1972 (Cesar). 1♀, MACN (19970), Ciudad Buenos Aires, Palermo [34°35’S, 58°26’W, 15 m], i.1931 (J.B. Daguerre). 2♀, MACN (12278), Reserva Natual Otamendi, Sección "Los Guardianes de la Barranca" (34°14.7’S, 58°53.7’W), 16 m, forest, 10.iii.2007 (C. Grismado et al.). 1 juv., MACN (12336), Reserva Natual Otamendi, “senderos varios”, 25.iii.2007 (C. Grismado).

Chaco: 1♂, MACN (72), Resistencia [27°27’S, 58°59’W, 50 m], without date, leg. J.B. Daguerre.GoogleMaps 

Description. Male (holotype)

MEASUREMENTS. Total body length 3.2, carapace width 1.3. Distance PME-PME 120 µm, diameter PME 110 µm, distance PME-ALE 80 µm, distance AME-AME 30 µm, diameter AME 40 µm. Sternum width/length: 0.9/ 0.55. Leg 1: 38.7 (10.1 + 0.5 + 9.7 + 16.3 + 2.1), tibia 2: 6.3, tibia 3: 4.6, tibia 4: 6.1; tibia 1 L/d: 81. Femora 1–4 width (at half length): 0.19, 0.20, 0.20, 0.18.

COLOR (in ethanol; specimen strongly bleached). Prosoma and legs pale ochre-orange, carapace with brown median band, ocular area light brown; clypeus not darkened; legs without dark rings; abdomen pale gray, with purple internal marks dorsally and laterally.

BODY. Habitus similar to members of the iguazu  group (cf. Figs 378, 380View FIGURES378–389); ocular area raised; carapace with distinct median furrow; clypeus and sternum unmodified.

CHELICERAE. With three pairs of frontal apophyses and rounded unsclerotized protrusion proximally near median line ( Figs 547–548View FIGURES 545–551).

PALPS. As in Figs 545–546View FIGURES 545–551; coxa with retrolateral apophysis; trochanter with small apophysis; femur with weakly sclerotized retrolateral process proximally, strongly widened distally; procursus strongly S-shaped, with distinctive tip; genital bulb process mostly unsclerotized.

LEGS. Without spines and curved hairs, few vertical hairs; retrolateral trichobothrium on tibia 1 at 3%; prolateral trichobothrium present on tibia 1; tarsus 1 with ~20 pseudosegments, barely visible in dissecting microscope.

Male (variation). Tibia 1 in four other males: 6.7, 8.7, 9.2, 9.6.

Female. In general similar to male. Tibia 1 in two females: 5.9, 6.4. Abdominal marks variably distinct, in one female absent. Epigynum as in Figs 549–550View FIGURES 545–551; posterior margin trilobed, without pocket, with series of anterior transversal sclerotized furrows; without posterior plate. Internal genitalia as in Fig. 551View FIGURES 545–551, with pore-plates in vertical lateral position and distinctive median structure.

Distribution. Known from Buenos Aires and Chaco provinces ( Argentina) ( Fig. 740View FIGURE 740).


Museo Argentino de Ciencias Naturales Bernardino Rivadavia