Mesabolivar amazonicus, 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 : 18-20

Mesabolivar amazonicus sp. n.

Figs 7–8 , 48–54 , 69–71

Diagnosis. Males are easily distinguished from known congeners by shape of procursus ( Fig. 49 ; distinctively widened and strongly curved distal element, much smaller than in similar species, i.e. M. acrensis , M. maraba , M. pseudoblechroscelis , M. huambisa ); also by armature of male chelicerae ( Figs 50–51 ; distinctive undulating shape of apophyses in lateral view), by shape of epigynum ( Figs 52–53 , 69–70 ; large median depression, lateral margins diverging toward anterior, bordered posteriorly by large pocket; pair of conical lateral processes; very similar to M. huambisa but median pocket reaching further back in lateral view), and by female internal genitalia ( Figs 54 , 71 ; similar to M. maraba and M. huambisa ; pore-plates larger and slightly curved towards posterior) (female of M. pseudoblechroscelis unknown).

Etymology. The specific name is an adjective derived from the type locality.

Type material. BRAZIL: Amazonas: ♂ holotype, 1♀ paratype, UFMG (21501–02), 2♂ 2♀ paratypes, ZFMK (Ar 18952), forest near Humaitá, ‘site 1’ (7.464°S, 63.231°W), 65 m a.s.l., 20.x.2016 (B.A. Huber, L.S. Carvalho).

Other material examined. BRAZIL: Amazonas: 1♀ 2 juvs in pure ethanol, ZFMK (Br 16-283), same data as types . 2♂ 3♀, ZFMK (Ar 18953), forest near Humaitá, ‘site 3’ (7.512°S, 63.393°W), 80 m a.s.l., 22.x.2016 (B.A. Huber, L.S. Carvalho); 2♀ in pure ethanol, ZFMK (Br 16-291), same data .

Description. Male (holotype)

MEASUREMENTS. Total body length 2.6, carapace width 1.2. Distance PME-PME 130 µm, diameter PME 120 µm, distance PME-ALE 90 µm, distance AME-AME 30 µm, diameter AME 55 µm. Sternum width/length: 0.95/ 0.55. Leg 1: 37.2 (9.0 + 0.5 + 9.0 + 16.3 + 2.4), tibia 2: 5.9, tibia 3: 4.3, tibia 4: 6.2; tibia 1 L/d: 86. Femora 1–4 width (at half length): 0.16, 0.17, 0.19, 0.16.

COLOR (in ethanol). Carapace ochre-yellow, with large slightly darker median mark, ocular area also slightly darkened; sternum ochre-orange; legs ochre to light brown, with indistinct darker rings on femora (subdistally) and tibiae (proximally and subdistally), tips of femora and tibiae lighter; abdomen greenish-gray, with dark internal marks dorsally and laterally, small ventral mark behind gonopore.

BODY. Habitus as in Fig. 7 ; ocular area raised (higher than usual in the genus); carapace with distinct median furrow; clypeus slightly swollen and whitish, with sclerotized margin; sternum unmodified.

CHELICERAE. With pair of long cylindrical apophyses, undulating in lateral view, with strongly sclerotized hooked tips ( Figs 50–51 ).

PALPS. As in Figs 48–49 ; coxa with conical retrolateral apophysis; trochanter with retrolateral apophysis; femur very large, proximally with retrolateral apophysis and prolateral ridge set with short hairs; tarsus with small dorsal processes, with one strong and two regular hairs bent towards dorsal; procursus distally widened and strongly curved towards dorsal; bulb with distally bifid process.

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 ~30 pseudosegments, distally fairly distinct.

Male (variation). Tibia 1 in three other males: 8.8, 8.9, 9.2. Prosoma variably orange.

Female. In general similar to male ( Fig. 8 ) 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 six females: 5.5–6.0 (mean 5.8). Epigynum as in Figs 52–53 , 69–70 ; anterior plate with large median depression bordered posteriorly by large pocket; pair of conical lateral processes directed slightly towards anterior; posterior plate large, simple. Internal genitalia as in Figs 54 , 71 , with elongated transversal pore-plates and distinctive median anterior structure.

Natural history. The spiders were found in small sheltered spaces in the leaf litter, under logs, or in small cavities in the ground.

Distribution. Known from type locality and a nearby site only, both in Amazonas state ( Brazil) ( Fig. 722 ).

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.

FIGURES 48–54. Mesabolivar amazonicus sp. n. (ZFMK Ar 18952). 48–49. Left male palp, prolateral and retrolateral views (arrowspoint at curved hairs on pedipalpal tarsus).50–51. Malechelicerae,lateral and frontalviews.52–53.Epigynum,ventral and lateral views. 54. Cleared female genitalia, dorsal view.Scale lines: 0.5.

FIGURES 69–77. Female epigyna in ventral and lateral views and cleared female genitalia, dorsal views, Mesabolivar pseudoblechroscelis group (part 2). 69–71. M. amazonicus sp. n. (ZFMK Ar 18952). 72–74. M. jamari sp. n. (ZFMK Ar 18954).75–77.M.tapajos sp. n. (ZFMK Ar 18958).

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.