Megalostrata Karsch, 1880

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 : 496-497

Megalostrata Karsch, 1880

Megalostrata Karsch, 1880: 377 ;

type species by monotypy, M. venifica Karsch, 1880 [

synonymized with Megalostrata raptor (L. Koch, 1866) by Bonaldo (2000)]. For a complete list of synonyms see Bonaldo (2000: 116).

Diagnosis. Megalostrata appears to be most closely related to Erendira Bonaldo, 2000 with which it shares a prolateral tegular process that is apical in relation to the embolus insertion ( Figs 3A, C , 20A, B , 22A, B ; Bonaldo 2000: figs 110–113, 304, 314) and the epigynum with an unsclerotized dorsal vulval plate and highly modified posterior plate ( Figs 5C , 8C , 12C , 22D ; Bonaldo 2000: figs 309, 323). Erendira also have dimorphic chelicerae, being longer in males than in females, but the male chelicerae of Erendira are not as modified as in Megalostrata ( Figs 1 , 2 , 4A, C , 15A, C ; see also Bonaldo 2000: figs 303, 312). Representatives of Megalostrata are readily separated from those of Erendira by presenting porrect male chelicerae, with only two large retromarginal teeth ( Figs 2B , 17B ; Bonaldo 2000: fig. 303) (male chelicerae not porrect, with three to four unmodified retromarginal teeth in Erendira ), male palpal tegulum without a conductor and with a highly coiled spermatic duct ( Figs 3A, C , 20 , 22A, B ) (hyaline conductor and uncoiled spermatic duct, with terminal portion adjacent to the second fold in Erendira , see Bonaldo 2000: figs 314, 320); female epigynum with posterior plate excavated medially, exposing the unsclerotized cuticle of the epigastric plate ( Figs 5C , 6E , 8C , 9E , 12C , 13E , 22D , 24C ) (posterior plate not medially excavated, with a pair of accessory lateral pockets in Erendira , see Bonaldo 2000: figs 317, 323). Species of Megalostrata also have a distinctive body color pattern, generally with contrasting stripes on the carapace, and yellowish-white and black patches or lines on the abdomen of both sexes, features that are easily visible in living specimens ( Fig. 1 ).

Description. See Bonaldo (2000: 116).

Key to species of Megalostrata

1 Males [Those of M. monistica ( Chamberlin, 1924) , M. bruneri ( Bryant, 1936) and M. pacifica spec. nov. unknown]....... 2

- Females............................................................................................. 4

2(1) Retrolateral tibial apophysis bifid ( Figs 3C, D ; Bonaldo 2000: figs 310, 311)...... M. depicta (O. Pickard-Cambridge, 1895)

- Retrolateral tibial apophysis entire ( Figs 3A, B , 20A , 22A, B ; Bonaldo 2000: figs 304–306).......................... 3

3(2) Apex of tegular process rounded, devoid of teeth; embolus directed retro-basally ( Figs 3A, B ; Bonaldo 2000: figs 304–306)................................................................................ M. raptor (L. Koch, 1866)

- Apex of tegular process truncated, with small teeth; embolus directed retro-apically ( Figs 20 , 22A, B , 23A, B )............................................................................................. M. paludosa spec. nov.

4(1) Secondary spermathecae elongated, tube-shaped ( Figs 5A, B , 6A–D , 8A, B , 9A–D ; Bonaldo 2000: fig. 309)............. 5

- Secondary spermathecae bulbous ( Figs 12A, B , 13A–D , 14C , 22C, E , 23C, D , 24A, B ).............................. 7

5(4) Secondary spermathecae oriented obliquely ( Figs 5A, B , 6A–D ; Bonaldo 2000: figs 308, 309)........................ 6

- Secondary spermathecae oriented longitudinally ( Figs 8A, B , 9A–D )........................... M. pacifica spec. nov.

6(5) Posterior atrium defined by a transversal anterior ridge at the level of copulatory openings ( Bonaldo 2000: fig. 308)....................................................................................... M. raptor (L. Koch, 1866)

- Posterior atrium borders ill-defined, transversal anterior ridge absent ( Figs 5A, B , 6A–D )................................................................................................ M. depicta (O. Pickard-Cambridge, 1895)

7(4) Copulatory openings wide, leading to long, curved anteriorly copulatory ducts; posterior margin of epigynal plate with a median invagination ( Figs 10C , 12A , 13A, C )..................................... M. monistica ( Chamberlin, 1924)

- Copulatory openings inconspicuous, copulatory ducts short; posterior margin of epigynal plate without median invagination ( Figs 14C , 22C )...................................................................................... 8

8(7) Primary spermathecae small (diameter near the atrium height), positioned anteriorly to posterior atrium ( Fig. 14C )........................................................................................ M. bruneri ( Bryant, 1936)

- Primary spermathecae large (diameter larger than the atrium height), positioned at the level of posterior atrium ( Figs 22C , 23C , 24A, B )........................................................................... M. paludosa spec. nov.

Figures

FIGURE 1. Living specimens of Megalostrata Karsch, 1880. A Megalostrata raptor (L. Koch, 1866), male (not collected) from Reserva Natural Miraflor, Nicaragua, photo by A. Anker; B Megalostrata depicta (O. Pickard-Cambridge, 1895), male (CHNUFPI 1485) from Estación de Biología Tropical “Los Tuxtlas”, Veracruz, Mexico, photo by L. S. Carvalho.

FIGURE 2. Megalostrata raptor (L. Koch, 1866), male (UNAM INVPIC071): A dorsal view; B ventral view; C lateral view. Scale bar: 2 mm.

FIGURE 3. A, B Megalostrata raptor (L. Koch, 1866), male (UNAM INVPICV071):A palp, ventral view. B palp, retrolateral view; C, D Megalostrata depicta (O. Pickard-Cambridge, 1895), male (UNAM CORINN0039): C palp, ventral view. D palp, retrolateral view. Abbreviations: E, embolus; RTA, retrolateral tibial apophysis; TP, tegular process. Scale bar: 2 mm.

FIGURE 4. Megalostrata depicta (O. Pickard-Cambridge, 1895) (UNAM CORINN0039): A male, dorsal view; B female, dorsal view; C male, lateral view. Scale bar: 2 mm.

FIGURE 5. Megalostrata depicta (O. Pickard-Cambridge, 1895), female epigynum: A ventral view; B dorsal view; C posterior view. Scale bar: 0.2 mm.

FIGURE 6. Megalostrata depicta (O. Pickard-Cambridge, 1895), female epigynum: A, C ventral view; B, D dorsal view; E, F posterior view (A, B, E undigested; C, D, F digested; A, B, E, F IBSP 226286; C, D UNAM INVPICV071).Abbreviations. CO, copulatory opening; CD, copulatory duct; FD, fertilization ducts; S1, primary spermathecae; S2, secondary spermathecae; EPC, epigastric plate cuticle. Scale bars: 0.2 mm.

FIGURE 8. Megalostrata pacifica spec. nov.: female holotype (CAS 9036847): A epigynum, ventral view; B same, dorsal view; C same, posterior view. Scale bars: 0.2 mm.

FIGURE 9. Megalostrata pacifica spec. nov., female holotype, epigynum (CAS 9036847):A, C ventral view; B, D dorsal view; E, F posterior view (A, B, E undigested; C, D, F digested). Abbreviations: CO, copulatory opening; FD, fertilization ducts; S1, primary spermathecae; S2, secondary spermathecae; PeP, posterior epigynal plate; EPC, epigastric plate cuticle. Scale bars: 0.2 mm.

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 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 15. Megalostrata paludosa spec. nov., male holotype (A, C) and female paratype (B, MUSEUV 2792):A male, dorsal view; B female, ventral view; C male, lateral view. Scale bars: 1 mm.

FIGURE 17. Megalostrata paludosa spec. nov., male (MPEG 39056): A mouthparts; B right chelicerae, ventral view; C left chelicerae, retrolateral view; D same, teeth. Abbreviations: FF fang furrow; QPT cheliceral promarginal teeth. Scale bars. A, D 500 μm; B, C 1000 μm.

FIGURE 20. Megalostrata paludosa spec. nov., male (MPEG 39056), right palp: A ventral view; B retro-ventral view; C embolus,ventral; D tegular process, ventral.Abbreviations:CRP, cymbial retrolateral basal process; E, embolus; RTA,retrolateral tibial apophysis; T, tegulum; TP, tegular process; St, subtegulum. Scale bars. A, B 500 μm; C 100 μm; D 50 μm.

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 23. Megalostrata paludosa spec. nov.. A, B male holotype: A palp, ventral view; B palp, retrolateral view. C, D female paratype (MUSEUV 2796): C epigynum, ventral view; D same, dorsal view. Abbreviations: CO, copulatory opening; CRP, cymbial retrolateral basal process; E, embolus; FD, fertilization ducts; RTA, retrolateral tibial apophysis; S1, primary spermathecae; S2, secondary spermathecae; TP, tegular process. Scale bars. A, B 0.5 mm, C, D 0.2 mm

FIGURE 24. Megalostrata paludosa spec. nov., A, C, D female paratype (MUSEUV 2796), B female paratype (MPEG 39054): A undigested epigynum, ventral view; B same, ventral view, variation; C same, posterior view; D same, digested, posterior view. Abbreviations: CO, copulatory opening; EPC, epigastric plate cuticle. Scale bars. 0.2 mm.