Mesabolivar tandilicus ( Mello-Leitão, 1940 ), Mello-Leitao, 1940

Machado, Éwerton O., Laborda, Álvaro, Simó, Miguel & Brescovit, Antonio D., 2013, Contributions to the taxonomy and distribution of the genus Mesabolivar in southern South America (Araneae: Pholcidae), Zootaxa 3682 (3), pp. 401-411 : 402

Mesabolivar tandilicus ( Mello-Leitão, 1940)

Figs 1–14

Litoporus tandilicus Mello-Leitão, 1940: 9 –10, figs 10–12, (Syntypes: two females, one without epigynum, and one male without palps and chelicerae from Tandil, Buenos Aires, Argentina, XII.1938, M. Birabén leg., in Museo de La Plata, number 14275 examined); Mello-Leitão, 1944: 312.

Mesabolivar tandilicus: Huber, 2000: 214 –215, figs 828–829; Platnick, 2012.

Notes. The female syntypes of M. tandilicus were redescribed by Huber (2000) but the male syntype was found to be severely damaged, lacking chelicerae and palps ( Huber, 2000). The original description ( Mello-Leitão, 1940) does not present useful drawings of the male genitalia. The female Uruguayan specimens were compared with the female types, and the corresponding males were used for the redescription.

Diagnosis. The male can be distinguished from congeners by the position of the prolateral cheliceral apophysis ( Figs 1–3 ) combined with the subdivided and membranous tip of the procursus ( Figs 4–6 ). The female can be distinguished from congeners by the low epigynum ( Fig. 9 ), the anterior position of the epigynal pocket and the pair of small posterior apophysis ( Figs 8–9 ).

Description. Male (FCE 1151). Total length 1.95, carapace width 0.9; leg I: 17.4 (4.9 + 0.4 + 4.6 +6.1 + 1.4), tibia II: 2.9, tibia III: 2.2, tibia IV: 2.9, tibia I L/d: 42. Carapace yellow with a dark dorsal longitudinal stripe; sternum yellow. Thoracic groove distinct. Eight eyes on a slightly elevated area; PME-ALE distance about 90% of PME diameter. Chelicerae uniformly light brown, basal segment with long and pointed proximal prolateral apophysis, with tip curved ventrally, proximally perpendicular to chelicerae ( Figs 1–3 ). Palp as in Fig. 4 . Coxa with retrolateral apophysis truncated ( Fig. 4 ). Femur with retrolateral proximal apophysis small and rounded ( Fig. 4 ). Procursus brown, narrow and curved towards dorsally ( Fig. 4 ), with two prolateral hairs. Procursus tip distinct, several membranous projections ( Figs 5–6 ). Bulb simple, without transparent projection, embolic division membranous ( Fig. 7 ). Legs yellowish-brown; without spines, without modified hairs. Tarsus I with 22 pseudosegments. Abdomen almost globular, yellow with some darker lateral spots.

Female. Redescribed by Huber (2000: 214–215, figs 864–868).

Distribution. Known from northeastern Argentina and Uruguay ( Fig. 41 ).

New records. URUGUAY: Treinta y Tres: Santa Clara de Olimar (32°55ʹS, 54°58ʹW), 23, 2Ƥ, 09.II.1960, L. Zolessi leg., under stones (FCE 655); Río Negro: Fray Bentos, near bridge "General San Martín" (33°07ʹ57ʺS, 58°17ʹ44ʺW), 43, 3Ƥ, 16.XII.2008, A. Laborda leg. (FCE 2843); Canelones: Rincón del Colorado, INIA Las Brujas (34°37ʹ59ʺS, 56°19ʹ59ʺW), 13, 6Ƥ, 07.X.2004 (FCE 1778, 1132, 2831, 2832, 2833); 13, 2Ƥ, 23.X.2004 (FCE 1182, 1151); 1Ƥ, 09.XI.2004 (FCE 1409); 1Ƥ, 25.XI.2004 (FCE 1534); 13, 5Ƥ, 11.XII.2004 (FCE 1637, 1653, 1665, 1678); 1Ƥ, 27.XII.2004 (FCE 1784); 1Ƥ, 12.I.2005 (FCE 2069); 13, 13Ƥ, 1j, 02.II.2005 (FCE 3048, 3056, 3085, 3105, 3080, 3096; IBSP 163027); 1Ƥ, 19.II.2005 (FCE 2834); 13, 07.III.2005 (FCE 3287), all collected by M. Simó.

Natural history. Most of the specimens collected in Uruguay were sampled with pitfall traps in grassland areas and agroecosystems, suggesting a ground-level habitat.

Figures

FIGURE 41. Known geographic distributions of Mesabolivar tandilicus, M. charrua sp. nov. and M. uruguayensis sp. nov..

FIGURES 1 – 10. Mesabolivar tandilicus. 1 – 3. Male chelicerae, frontal (1), lateral (2), dorsal (3). 4, Male left palp, retrolateral. 5 – 6, Procursus tip, prolateral (5), dorsal (6). 7, Bulb, prolateral. 8 – 10. Epigynum, ventral (8), lateral (9), dorsal (10). Scale: 0.5 mm; except fig. 5 – 6: 0.25 mm.

FIGURES 11 – 14. Mesabolivar tandilicus, scanning electron micrographs. 11, Male chelicerae. 12, Tarsal organ, left palp. 13, Left procursus tip, prolateral. 14, Embolic division, left bulb, prolateral.