Mesabolivar constrictus, 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 : 115

Mesabolivar constrictus sp. n.

Figs 454–456 , 498–505 , 532

Diagnosis. Easily distinguished from most congeners (except M. saci ) by subdistal constriction of male chelicerae ( Fig. 498 ); also by details of male palp (procursus S-shaped in dorsal view, Fig. 499 ; femur very large relative to tibia; cf. Fig. 490 ), and by shape of epigynum ( Figs 501–504 ; anterior plate with pair of large processes, median pocket, and small median anterior process); from the very similar M. saci by tip of procursus in frontal view (compare Figs 491 , 499 ), by absence of proximal anterior processes on male chelicerae (compare Figs 493 , 500 ), and by pair of epigynal processes strongly bent backwards (compare Figs 495 , 504 ).

Etymology. The specific name refers to the unusual constriction in the male chelicerae (Latin constrictus = compressed, squeezed, contracted); adjective.

Type material. BRAZIL: Santa Catarina: ♂ holotype, 1♀ paratype, UFMG (21534–35), 3♂ 4♀ paratypes, ZFMK (Ar 19208), Três Barras National Forest (26.242°S, 50.301°W), 800 m a.s.l., 14.x.2014 (B.A. Huber, L.S. Carvalho).

Other material examined. BRAZIL: Santa Catarina: 5♀ in pure ethanol, ZFMK (Br14-146), same data as types.

Description. Male (holotype)

MEASUREMENTS. Total body length 1.8, carapace width 0.87. Distance PME-PME 80 µm, diameter PME 80 µm, distance PME-ALE 60 µm, distance AME-AME 20 µm, diameter AME 25 µm. Sternum width/length: 0.67/ 0.47. Leg 1: 8.8 (2.0 + 0.3 + 2.1 + 3.0 + 0.7), tibia 2: 1.4, tibia 3: 1.1, tibia 4: 2.1; tibia 1 L/d: 23. Femora 1–4 width (at half length): 0.18, 0.24, 0.24, 0.17.

COLOR (in ethanol). Prosoma and legs ochre-yellow, legs without light or dark rings; abdomen dorsally and laterally densely covered with dark bluish marks, ventrally pale greenish gray with light brown marks in front of gonopore and in front of spinnerets.

BODY. Habitus as in Fig. 454 ; ocular area raised; carapace with shallow but distinct median furrow; clypeus unmodified; sternum unmodified.

CHELICERAE. With pair of strong frontal processes and distinctive subdistal constriction ( Figs 498, 500 ).

PALPS. In general very similar to M. saci (cf. Figs 489–490 ); only procursus in dorsal view clearly different ( Fig. 499 ).

LEGS. Without spines and curved hairs, few vertical hairs; retrolateral trichobothrium on tibia 1 at 8.5%; prolateral trichobothrium present on tibia 1; tarsus 1 with ~15 pseudosegments, distally fairly distinct.

Male (variation). Tibia 1 in three other males: 2.0, 2.1, 2.1. One male with whitish abdomen ( Fig. 455 ).

Female. In general similar to male. Tibia 1 in five females: 1.6–1.9 (mean 1.8). Epigynum as in Figs 501–504 ; complex anterior plate with small anterior median process, median pocket, and pair of large processes strongly bent backwards; posterior plate anteriorly raised. Internal genitalia as in Figs 505 , 532 , very small relative to external genitalia, with pair of round pore-plates close together.

Natural history. The spiders were found in relatively humid places under logs and branches on the ground, in tiny webs built in small holes in the ground. One egg sac contained ~ 10 eggs.

Distribution. Known from type locality in Santa Catarina state ( Brazil) only ( Fig. 739 ).

Figures

FIGURES 447–458. Live specimens, Mesabolivar difficilis group (part 1). 447–448. M. itajai sp. n., male and female from Itajaí.449–451.M.niteroi sp. n., males and female from St.Hilaire/Lange. 452–453. M.saci sp. n., male and female from São Joaquim. 454–456. M. constrictus sp. n., males (regular color and white abdomen morph) and female from Três Barras. 457– 458.M.sepitus sp. n., male and female from Serra Geral.

FIGURES 498–505. Mesabolivar constrictus sp. n. (ZFMK Ar 19208). 498, 500. Male chelicerae, frontal and lateral views. 499. Left procursus, dorsal view. 501–504. Epigynum, ventral, posterior, frontal, and lateral views. 505. Cleared female genitalia, dorsal view.Scale lines:0.3.

FIGURES 520–537. Female epigyna in various views and cleared female genitalia in dorsal views, Mesabolivar difficilis group. 520. M. itajai sp. n. (ZFMK Ar 19197). 521. M. niteroi sp. n. (ZFMK Ar 19198). 522–524. M.difficilis (Mello-Leitão, 1918) (ZFMK Ar 19201), epigyna in lateral, frontal, and posterior (slightly ventral) views. 525–530. M. sp. (“M. difficilis” in Bonaldo et al. 2009) from Presidente Figueiredo (525–527, ZFMK Ar 19205) and from Manaus (528–530, SMNK-ARA 12794) (522–530 at same scale and in same views). 531. M. saci sp. n. (ZFMK Ar 19207). 532. M. constrictus sp. n. (ZFMK Ar 19208). 533. M. sepitus sp. n. (ZFMK Ar 19210). 534–537. M. cavicelatus Machado et al., 2007 (epigyna: ventral views), from Penedo (534–535, ZFMK Ar19215) and from Ubatuba (536–537, ZFMK Ar 19218).

FIGURES 489–493. Mesabolivar saci sp. n. (ZFMK Ar 19207). 489–490. Left male palp, prolateral and retrolateral views. 491. Left procursus, dorsal view. 492–493. Male chelicerae, frontal and lateral views. Scale lines: 0.5 (489–490), 0.3 (491– 493).

FIGURES 494–497. Mesabolivar saci sp. n. (ZFMK Ar 19207). 494–496. Epigynum, ventral, lateral, and frontal views. 497. Cleared female genitalia, dorsal view.Scale lines:0.3.

FIGURES 738–739. Known distribution of the Mesabolivar difficilis group.