Megalostrata monistica ( Chamberlin, 1924 )

Bonaldo, Alexandre B., Galán-Sanchez, M. Antonio & García, Fabián, 2024, Advances on the taxonomy of Megalostrata Karsch, 1880 (Araneae, Corinnidae, Corinninae), with descriptions of two new species, Zootaxa 5458 (4), pp. 495-523 : 507-509

Megalostrata monistica ( Chamberlin, 1924)

Figs 10–13

Chemmis monisticus Chamberlin, 1924: 667 , fig. 111 (♀ holotype Hermosillo , San Pedro Bay Sonora, Mexico [28°04’01.2”N 111°14’34.8”W], leg. J.C. Chamberlin, 7.VII.1921, CAS 1451 ). Examined by photos.

Megalostrata monistica ; Bonaldo 2000: 118 (by genus synonymy).

Diagnosis. Females of M. monistica are similar to those of M. paludosa spec. nov. and M. bruneri by the short, bulbous secondary spermathecae ( Figs 14C , 22C, E ) but can be readily recognized by the wide copulatory openings directed posteriorly, toward the posterior atrium, leading to long, curved copulatory ducts, and by the posterior margin of the epigynal plate with an accentuated median invagination ( Figs 12A, B , 13A–D ).

Description. Male. Unknown. Female (CAS 9119037): Carapace yellowish-orange, cephalic region with two wide, undefined reddish-brown stripes. Chelicerae, labium, and endites reddish-brown. Sternum yellowish-white. Legs yellowish-orange. Abdomen dorsum yellowish-white. Total length 9.350. Carapace 4.338 long, 3.407 wide. Clypeus height 0.200. Eye diameters:AME 0.278, ALE 0.251, PME 0.213, PLE 0.194. Interocular distances: AME-AME 0.247, AME-ALE 0.198, PME-PME 0.259, PME-PLE 0.284 ALE-PLE 0.065. Chelicerae 1.831 long, 0.929 wide, with three promarginal and two retromarginal teeth, Sternum 2.087 long, 2.025 wide. Leg measurements: I—4.494, 1.655, 3.147, 3.174, 1.377, 13.847; II—4.614, 1.655, 3.147, 3.174, 1.220, 13.810; III—3.648, 1.138, 3.360, 3.722, 1.483, 13.351; IV—4.118, 1.646, 3.639, 4.661, 0.765, 14.829. Leg spination: I—femur d1-2-2, p0- 1-0; tibia p1-1, r1-1; metatarsus v1-1-1-1-1. II—femur d1-2-2; tibia p1-1, r1-1; metatarsus v1-1-1-1-1. III—femur d1-1-1, p0-1-1; tibia p1-1; metatarsus d2-2-2, v1-1-1, p1-1-1, r1-1-1. IV—femur v0, d2-1-1-1, r1-1; tibia p1-1, r1-1; metatarsus d2-2-0, r1-1. Abdomen 5.012 long, 1.946 wide. Epigynum. Epigynal plate subtriangular, anterior portion convex, posterior atrium borders ill-defined, transversal anterior ridge absent; posterior margin of epigynal plate with accentuated median invagination; margin of posterior plate excavation strongly procurved in posterior view, copulatory openings large. Copulatory ducts long, curved anteriorly; secondary spermathecae small, bulbous; primary spermathecae globular, positioned posteriorly to copulatory openings, diameter smaller than atrium height; fertilization ducts directed anteriorly ( Figs 12 , 13 ).

New record. MEXICO: Nayarit: 15 km N of Peñas [21°51’32.4”N 105°11’49.2”W], leg. E. S. Ross, 26.XI.1948, 1 ♀ ( CAS 9119037 ) .

Distribution. Mexican west coast (Sonora and Nayarit) ( Fig. 25 ).

Figures

FIGURE 10. Megalostrata monistica (Chamberlin, 1924), female holotype:A dorsal view. B ventral view; C epigynum, ventral view. Scale bars: A,B 2 mm; C 0.5 mm.

FIGURE 11. Megalostrata monistica (Chamberlin, 1924), female, Nayarit, Mexico (CAS 9119037): A dorsal view. B ventral view; C lateral view. Scale bars: 3 mm.

FIGURE 12. Megalostrata monistica (Chamberlin, 1924): female, Nayarit, Mexico (CAS 9119037):A epigynum, ventral view; B same, dorsal view; C same, posterior view. Scale bars: 0.2 mm.

FIGURE 13. Megalostrata monistica (Chamberlin, 1924), female, Nayarit, Mexico (CAS 9119037), epigynum: A, C ventral view; B, D dorsal view; E, F posterior view (A, B, E undigested; C, D, F digested).Abbreviations. CO, copulatory opening; CD, copulatory duct; FD, fertilization ducts; S1, primary spermathecae; S2, secondary spermathecae; PeP, posterior epigynal plate; EPC, epigastric plate cuticle. Scale bars. 0.2 mm.

FIGURE 14. Megalostrata bruneri (Bryant, 1936), female holotype (MCZ): A dorso-lateral view; B abdomen, ventral view; C epigynum, ventral view. Scale bars: A 5 mm, B 1 mm, C 0.5 mm.

FIGURE 22. Megalostrata paludosa spec. nov.. A, B male holotype:A palp, ventral view; B palp, retrolateral view. C–E female paratype (MUSEUV 2796): C epigynum, ventral view; D same, posterior view; E same, dorsal view. Scale bars. 0.2 mm.

FIGURE 25. Known geographical distribution of Megalostrata species.