Mesabolivar maraba, Huber, 2018

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 : 16-17

Mesabolivar maraba sp. n.

Figs 3–4 , 16–17 , 23–25 , 39–41

Diagnosis. Males are easily distinguished from two most similar known relatives ( M. pseudoblechroscelis , M. acrensis ) by male pedipalp (procursus with distinctively shaped distal element; bulbal process with ventral sclerotized area and bifid dorso-distal flap; Figs 16–17 ); from most species (except M. pseudoblechroscelis , M. acrensis , M. huambisa ) also by armature of male chelicerae (identical in shape to those of M. acrensis , cf. Figs 18– 19 ; pair of slender apophyses, straight in lateral view), and by shape of epigynum ( Figs 23–24 ; large median depression, lateral margins slightly diverging towards anterior, bordered posteriorly by large pocket; pair of conical lateral processes directed slightly towards posterior - epigynum possibly indistinguishable from M. acrensis , due to variation, see description of M. acrensis above); from M. acrensis and other putatively close relatives also by female internal genitalia ( Figs 25 , 39 ; elongated pore-plates in transversal position, wider apart than in M. huambisa ) (female of M. pseudoblechroscelis unknown).

Etymology. The specific name is derived from the type locality; noun in apposition.

Type material. BRAZIL: Pará: ♂ holotype, 1♀ paratype, UFMG (21499–21500), 5♂ 6♀ paratypes, ZFMK (Ar 18948), Marabá, forest near road, ‘site 1’ (5.414°S, 49.074°W), 140 m a.s.l., 7–8.x.2016 (B.A. Huber, L.S. Carvalho).

Other material examined. BRAZIL: Pará: 3♀ in pure ethanol, ZFMK (Br16-238), same data as types.

Assigned tentatively. BRAZIL: Amapá: 1♂ 1♀, ZFMK (Ar 18949), forest SW Macapá, ‘site 4’ (0.057°S, 51.234°W), 25 m a.s.l., 13.x.2016 (B.A. Huber, L.S. Carvalho) ; 2♀ in pure ethanol, ZFMK (Br 16-255), same data .

Description. Male (holotype)

MEASUREMENTS. Total body length 2.7, carapace width 1.2. Distance PME-PME 140 µm, diameter PME 120 µm, distance PME-ALE 90 µm, distance AME-AME 55 µm, diameter AME 55 µm. Sternum width/length: 0.95/ 0.60. Leg 1: 36.2 (8.8 + 0.5 + 8.8 + 16.1 + 2.0), tibia 2: 6.1, tibia 3: 4.4, tibia 4: 6.3; tibia 1 L/d: 80. Femora 1–4 width (at half length): 0.15, 0.17, 0.20, 0.18.

COLOR (in ethanol). Carapace ochre-yellow, with large brown median mark, ocular area also darkened posteriorly laterally; sternum orange; legs ochre, with indistinct darker rings on femora (subdistally) and tibiae (proximally; subdistal rings barely visible), tips of femora and tibiae whitish; abdomen greenish, with dark internal marks dorsally and laterally, without ventral mark.

BODY. Habitus as in Fig. 3 ; ocular area raised (higher than usual in genus); carapace with distinct median furrow; clypeus slightly swollen, with sclerotized margin; sternum unmodified.

CHELICERAE. Identical in shape to M. acrensis (cf. Figs 18–19 ), but slightly larger.

PALPS. In general as in M. acrensis (cf. Figs 13–14 ), but larger (e.g., femur length: 1.14 vs. 0.86); procursus distally clearly different from M. acrensis ( Fig. 17 ); bulbal process with ventral sclerotized area and bifid dorsodistal flap ( Fig. 16 ).

LEGS. Without spines and curved hairs, few vertical hairs; retrolateral trichobothrium on tibia 1 at 2.5%; prolateral trichobothrium present on tibia 1; tarsus 1 with ~25 pseudosegments, distally fairly distinct.

Male (variation). Some males with indistinct dark mark behind gonopore. Tibia 1 in five other males from type locality: 7.1–10.2 (mean 8.7). The single male from Amapá has a slightly different procursus tip (slightly larger relative to base of procursus) and is therefore assigned tentatively (cf. female below). Tibia 1 in this male: 9.6.

Female. In general similar to male but carapace ochre-brown rather than yellow to orange, with larger brown median mark; ocular area slightly lower than in males; dark rings and whitish tips of femora and tibiae more distinct; clypeus less swollen and margin not sclerotized. Tibia 1 in seven females from type locality: 4.1–5.5 (mean 4.7). Epigynum as in Figs 23–24 and 40–41 ; anterior plate with large median depression bordered posteriorly by large pocket; pair of conical lateral processes directed slightly towards posterior; posterior plate large, simple. Internal genitalia as in Figs 25 , 39 , with elongated pore-plates in transversal position and far apart, and distinctive median dark anterior structure.

In the three females from Amapá, the margins of the median depression are approximately parallel and the conical lateral processes are slightly shorter; they are therefore assigned tentatively (cf. male above). tibia 1 in two females: 5.7 (both; legs 1 missing in third female).

Natural history. At Marabá, the spiders were mostly found under large palm leaves on the ground. In Macapá, they occupied small cavities in the ground and the spaces under the exposed roots of trees.

Distribution. Known from type locality in Pará state and from specimens assigned tentatively from Amapá state ( Brazil) ( Fig. 722 ).

Note. The illustrations in Machado (2011) of species “sp. 07” strongly remind of the present species. It is not clear which specimens were used for the illustrations: the types from Rio Branco (Acre) or the specimens from Floresta Nacional de Caxiuanã, Melgaço (Pará). The latter locality is approximately between and fairly close to the localities listed above (485 km from the type locality Marabá, 190 km from Macapá), while Rio Branco is more than 2100 km west and much less likely to have the same species.

Figures

FIGURES 1–12. Live specimens, Mesabolivar pseudoblechroscelis group. 1–2. M. acrensis sp. n., male and female from Rio Branco. 3–4. M. maraba sp. n., male and female from Marabá. 5–6. M. huambisa Huber, 2000, male from Tabatinga, female from Belém.7–8.M.amazonicus sp. n., male and female from Humaitá.9–10.M.jamari sp. n., male and female from Jamari. 11–12. M.tapajos sp. n., male and female from Tapajós.

FIGURES13–17.Mesabolivar acrensissp. n.(13–15, ZFMK Ar 18942)and M.maraba sp. n. (16–17,ZFMK Ar18948).13– 14. Left male palp, prolateral and retrolateral views. 15–16. Left bulbal processes, prolateral views (arrow points at distinctive sclerotized area). 17. Left procursus, retrolateral view. Abbreviations: b, genital bulb; bp, bulbal process; c, coxa; f, femur; p, procursus, ta, tarsus; ti, tibia; tr, trochanter.Scale lines:0.5 (13–14, 17), 0.3 (15–16).

FIGURES18–25. Mesabolivar acrensissp.n. (18–22; ZFMK Ar 18942–43) andM.maraba sp. n.(23–25, ZFMK Ar 18948). 18–19. Male chelicerae, frontal and lateral views. 20–21, 23–24. Epigyna, ventral and lateral views. 22, 25. Cleared female genitalia, dorsal views.Abbreviations:ep, epigynal pocket; pp, pore plate; v, ‘valve’. Scale lines:0.5.

FIGURES 32–47. Female epigyna in ventral and lateral views and cleared female genitalia, dorsal views, Mesabolivar pseudoblechroscelisgroup (part 1). 32–38. M. acrensissp. n., from Rio Branco (32–33, 38, ZFMK Ar 18943), Cruzeirodo Sul (34–37, ZFMK Ar 18946). 39–41. M. maraba sp. n. (ZFMK Ar 18948). 42–47. M. huambisa Huber, 2000, from Samiria (42– 43, MUSM), Tabatinga (44–45, ZFMK Ar 18950), and Belém (46–47, ZFMK Ar 18951).

FIGURES 722–723. Known distribution of the Mesabolivar pseudoblechroscelis group. For the dubious type locality of M. exlineae, see under description of M.jamari. TL, type locality.