Trechona diamantina, Guadanucci & Fonseca-Ferreira & Baptista & Pedroso, 2016

Guadanucci, José Paulo L., Fonseca-Ferreira, Rafael, Baptista, Renner Luiz Cerqueira & Pedroso, Denis Rafael, 2016, An unusual new species of Trechona (Araneae: Mygalomorphae: Dipluridae), from quartzitic caves of the Diamantina Plateau, Minas Gerais, Brazil, with a key to the known species, Journal of Natural History 50, pp. 2487-2497 : 2489-2495

Trechona diamantina sp. nov.

( Figures 1 – 3 ; Tables 1 – 3)

Material examined

Holotype male ( MZSP 67289 ) from Gruta do Salitre (18°16 ʹ 46.7 ʹʹ S, 43°32 ʹ 9.6 ʹʹ W), Diamantina, Minas Gerais, Brazil, 1 November 2014, R.F. Ferreira and C.S. Fernandes . Paratypes: 1 female ( MZSP 67290 ) from Lapa do Manéu (18°16 ʹ 20.5 ʹʹ S, 43°46 ʹ 57.1 ʹʹ W), Diamantina, Minas Gerais, Brazil, 19 February 2014, R .F. Ferreira and B.G.O. do Monte ; 1 female ( MZSP 67291 ) from Gruta Monte Cristo (18°11 ʹ 12.5 ʹʹ S, 43°47 ʹ 59.8 ʹʹ W), Diamantina, Minas Gerais, Brazil, December 2014, T .S. Pires. Other specimens: Diamantina: 1 juvenile ( MZSP 67294 ), Lapa dos Pombos (18°17 ʹ 11.8 ʹʹ S, 43°32 ʹ 0.6 ʹʹ W); 2 juveniles ( MZSP 67295 ), Monte Cristo Cave ; 2 juvenile females ( CAD 028), from Monte Cristo Cave, J .P.L. Guadanucci, September 2009.

Etymology

The specific epithet refers to the type locality, the Diamantina Plateau in central Minas Gerais State .

Diagnosis

Mature specimens of Trechona diamantina sp. nov. can be distinguished from congeners by the light reddish colouration of the carapace and by dark legs, palps and chelicerae in both sexes ( Figure 3 ). The new species is presumably closely related to T. uniformis , both possessing a long embolus and elongated receptacula without head or lateral branches, as well as transversal stripes that are almost touching or fused along the median line of the dorsal side of the abdomen. Males differ from those of T. uniformis by the piriform tegulum (vs. globular), and by the less elongated embolus (vs. much longer) ( Figure 1 (d – f)). Females differ from those of T. uniformis by the receptacula being less elongated, curved outwards and with a pointed apex ( Figure 2 (c – d)), in contrast to the very elongated S-shaped receptacula with a rounded apex in T. uniformis .

Description

Male (holotype) ( Figure 1 ; Table 1). Total length: 20.4. Carapace: length 9.5; width 8.2. Eye tubercle: length 0.6; width 1.6. Eye sizes: AME 0.3; ALE 0.5; PME 0.3; PLE 0.4. Labium: length 1.1; width 1.6. Sternum: length 4.0; width 3.7. Each cheliceral furrow

with 11 – 12 teeth on prolateral margin; basal article of chelicerae dark. Labium with 1 central cuspule. Palpal coxae (or maxillae) with 40 cuspules on ventral face; lyra composed of 12 large club-shaped setae followed by several rows of smaller setae in distal portion. Sternum rounded, posterior sigillae less than its diameter apart from sternum margin ( Figure 1 (c)). Spines: all tarsi without spines; palp: femur (d) ap2, patella (p)1, tibia (p) 1 – 1, (v)2 – 2 – r1; legs: I: femur (d) 2 – 3 – 4 – 3, patella (p) 1, (r) 1, tibia (p) 1 – 1, (v) 2 – 2, (r) 1 – 1 – 1, metatarsus (p) 1 – 1, (v) 1 – 1 – 1; II: femur (d) 3 – 3 – 3 – 2, patella (p) 1, tibia (v) 2 – 2 – ap2, (r) 1 – 1, (p) 1 – 1, metatarsus (p) 1, (v) 1 – 1 – 1 – ap1; III: femur (d) 3 – 3 – 3 – 2, patella (r) 1, (p) 1, tibia (d) 1 – 1, (r)1 – 1 – 1, (v) 2 – 2 – ap2, (p) 1 – 1, metatarsus (d) 1 – 1 – 1 – 1 – ap2, (r) 1 – 1, (v) 1 – 1 – 2 – ap3, (p) 1 – 1 – 1; IV: femur (d) 3 – 4 – 4 – 2, patella (r) 1, (p) 1, tibia (d) 1 – 1 – 1, (r) 1 – 1, (p) 1 – 1, (v) 2 – 2 – ap2, metatarsus (d) 1 – 1 – 1 – 2, (p) 1 – 1 – 1 – 1, (r) 1 – 1, (v) 2 – 1 – 1 – 1 – ap3. Carapace light reddish, with few grey setae, fovea tranversal, shallow and narrow, a bit recurved ( Figure 1 (a)). Anterior eye row straight,

leg articles (mm).

posterior one slightly recurved. Male palpal organ long and straight, tegulum pyriform ( Figure 1 (d – f)). Tibia I with single long megaspine on low spur located at retroventral-apical portion ( Figure 1 (h – i)). Metatarsus I with a small retrolateral nodule at its basal quarter ( Figure 1 (i), arrow). Paired tarsal claws bipectinated (each with two rows of teeth). Scopulae on ventral side of metatarsi: I 3/4 covered by scopula, II 2/3, III and IV 1/3. Scopulae on ventral side of tarsi: I and II without thick setae, III and IV with a longitudinal band of thick setae. All tarsi pseudosegmented. Legs and palps dark, with light reddish coxae and trochanters. Opisthosoma covered with stiff dark setae; five transversal stripes on dorsum, the two first wider and with a clear notch in the middle, first stripe separated by a tiny median gap, the other stripes fused over the median line of dorsum ( Figure 1 (b)). Palpal organ ( Figure 1 (d – f)) more than 50% of tibia length, c. 1.6× longer than wide; tegulum piriform, tapering distally and slightly slanted at transition to embolus in retrolateral view; embolus long, almost straight, slowly tapering towards apex in retrolateral view, apex bent retrolaterally in ventral view.

Female (paratype MZSP 67290) ( Figures 2 (a – c) and 3). Total length: 24.1. Carapace: length 11.0; width 8.9. Eye tubercle: length 0.8; width 1.7. Eye sizes: AME 0.3; ALE 0.6; PME 0.3; PLE 0.4. Labium: length 1.3; width 1.9. Sternum: length 4.7; width 4.1. Each cheliceral furrow with 10 – 12 teeth on the prolateral margin; basal article of chelicerae dark. Labium with 2 central cuspules. Palpal coxae with approximately 50 cuspules on ventral face; lyra composed of 13 club-shaped setae followed by several smaller setae in distal portion. Sternum similar to that of male ( Figure 2 (b)). Spines: all tarsi without spines; palp: femur (d) ap2; patella (p) 1; tibia (p) 1 – 1, (r) 1, (v) 2 – 2 – ap2; tarsus (v) 2; legs: I: femur (d) 1 – ap2; patella (p) 1, tibia (p) 1 – 1, (v) 1 – 1ap2; metatarsus (v) 1 – 2 – ap1; II: femur (d) ap1; patella (p) 1; tibia (p) 1 – 1, (v) 1 – 2 – ap2; metatarsus (p) 1, (v) 2 – 2 – ap2; III: femur (d) 2 – 3 – 2 – 2; patella (p) 1, (r) 1; tibia (p) 1 – 1, (r) 1 – 1 – 1, (v) 2 – 2 – ap2; metatarsus (d) 1 – 1 – 1 – ap1, (r) 2 – 2 – ap1, (p) 1 – 1, (v) 2 – 1 – 2 – ap3; IV: femur (d) 3 – 2 – 2 – 2, patella (p) 1, (r) 1; tibia (p) 1 – 1 – 1, (r) 1 – 1 – 1, (v) 2 – 2 – ap2; metatarsus (d) 1 – 1 – ap2, (r) 1 – 2, (p) 1 – 1, (v) 1 – 2 – 1 – 2ap3. Carapace and eyes similar to those of male, but fovea seemingly wider, slightly recurved ( Figures 2 (a) and 3). Paired tarsal claws bipectinated. Scopulae on ventral side of metatarsi: I and II totally covered by scopula, III half and IV ¼. Scopulae on ventral side of tarsi: I without thick setae, II – IV with a longitudinal band of thick setae. All tarsi pseudosegmented. Colour pattern and setae of abdomen, legs and palps similar to those of male, but first two transversal stripes not fused but almost touching each other in middle line ( Figure 3 ). Vulva composed of two long and narrow receptacula seminis curved outwards, their apices strongly tapering, curled, about 5 – 6× as long as wide, their bases separated by about their width ( Figure 2 (c – d)).

Variation

Female (paratype MZSP 67291) ( Figure 2 (d); Table 3). Total length: 27.8. Carapace: length 11.3; width 9.3. Eye tubercle: length 1.2; width 2.0. Eye sizes: AME 0.3; ALE 0.5; PME 0.3; PLE 0.4. Labium: length 1.5; width 2.2. Sternum: length 5.0; width 4.4.

Key to Trechona species

Males

1. Dorsum of abdomen with transversal stripes touching or fused with each other along midline, at most with minute gaps between them. Palpal organ 55 – 80% of length of palpal tibia, with elongated embolus ................................ 2

1 ʹ. Dorsum of abdomen with transversal stripes clearly separated, with distinct gaps between them, in some specimens two anterior stripes almost continuous. Palpal organ less than 50% of length of palpal tibia, with relatively short embolus ......................................................................................................................................... 3

2 (1). Carapace brown to dark brown. Palpal organ about 80% of length of palpal tibia. Bulb relatively short and wider than long. Embolus extremely elongate, approximately 4× as long as bulb (northeastern São Paulo, southwestern Rio de Janeiro and southeastern Minas Gerais)...................................... ...................................... T. uniformis

2 ʹ. Carapace light reddish. Palpal organ about 55% of length of palpal tibia. Embolus moderately elongated, approximately 1.6× as long as bulb (Diamantina Plateau, Minas Gerais)...................................... ...................................... Trechona diamantina sp. nov.

3 (1 ʹ). Live or recently preserved specimens with uniformly reddish brown to brownish body. Palpal coxae with up to 33 cuspules. Metatarsus I with area above its basis slightly thinner than rest of article and with retrolateral protuberance clearly visible, placed at same distance from article basis as the retroventral spine of tibia I ( Pedroso et al. 2008, fig. 2 – 3). Bulb globose, with an inner hump; embolus inserted slightly laterally on bulb in frontal view ( Pedroso et al. 2008, fig. 5 – 8) (state of São Paulo)................................................................................................................ T. rufa

3 ʹ. Live or recently preserved specimens with uniformly dark brown to black body. Palpal coxae with at least 40 cuspules. Metatarsus I with area just above its basis much thinner than rest of article and its retrolateral protuberance very small, indistinct, due to the thickening of the whole area around the ventral spine ( Pedroso and Baptista 2004, fig. 3 – 4). Bulb piriform, regularly narrowing towards base of embolus in frontal view ( Pedroso and Baptista 2004, fig. 5 – 8) (states of Rio de Janeiro, Espírito Santo and Minas Gerais)........................... ........................... T. venosa

Females

1. Dorsum of abdomen with transversal stripes contiguous or fused along midline, at most with minute gaps between them. Receptacula seminis elongate, without heads (distal widenings) or side branches .............................................................................. 2

1 ʹ. Dorsum of abdomen with transversal stripes clearly separated, with distinct gaps between them, in some specimens two anterior stripes almost contiguous. Receptacula seminis relatively short, each with a distinct head and usually with one long side branch or at least a small knob on its inner side................... 3

2. (1 ʹ). Carapace brown to dark brown. Receptacula seminis extremely elongate, S-shaped, continuously tapering to a rounded apex, over 8× as long as wide; bases of receptacula separated from each other by approximately twice their width.............................................................................................................................. T. uniformis

2 ʹ. Carapace light reddish. Receptacula elongate, curved outwards, in distal fourth abruptly tapering to a pointed apex, about 5 – 6× as long as wide; bases of receptacula seminis separated from each other by approximately their width.... ..................................................................................................... Trechona diamantina sp. nov.

3 (1 ʹ). Live or recently preserved specimens with uniformly dark brown to black body. Abdomen with chevron pattern formed by wide and clearly visible transversal stripes on dorsum and with additional smaller lateroventral stripes placed between dorsal stripes. Cuspules on palpal coxae varying from 50 to 60. Tarsus III with undivided scopula, rarely with a few black setae in distal portion of article in adult females, but immature specimens with divided scopula ( Pedroso and Baptista 2004, fig. 2). Each receptaculum seminis with a relatively small rounded head separated from stalk by a relatively wide and short neck, the latter usually with a distinct outer (ectal) knob ( Pedroso and Baptista 2004, fig. 1)................................................................. ................................................................. T. venosa

3 ʹ. Live or recently preserved specimens with uniformly reddish brown to brownish body. Chevron pattern formed by relatively thin and not very contrasting transversal stripes, without additional lateral stripes. Palpal coxae with up to 33 cuspules. Tarsus III with scopula divided by rows of long black setae at least in distal half of article in immature and adult specimens ( Pedroso et al. 2008, fig. 1). Each receptaculum seminis usually with a relatively large, egg-shaped head tapering at its inner (ental) side, which is much thinner than the outer side, separated from stalk by a long and thin neck without an outer knob ( Pedroso et al. 2008, fig. 4)................................................................................................................ T. rufa

Figures

Figure 1. Trechona diamantina sp. nov., male holotype. (a) Cephalothorax, dorsal view. (b) Abdomen, dorsal view. (c) Cephalothorax, ventral view. (d) Palpal organ, retrolateral view. (e) Same, ventral view. (f) Same, prolateral view. (g) Palpal coxa, prolateral view showing lyra. (h) Right tibia and metatarsus I, retrolateral view. (i) Right tibia and metatarsus I, ventral view, arrow pointing to retrolateral nodule. Scale bars = 1 mm.

Figure 2. Trechona diamantina sp. nov. (a–c) female paratype MZSP 67,290. (a) Cephalothorax, dorsal view. (b) Cephalothorax, ventral view. (c) Vulva, dorsal view. (d) Vulva, dorsal view, female paratype MZSP 67,291. Scale bars = 1 mm.

Figure 3. Trechona diamantina sp. nov., female from Monte Cristo cave, Diamantina, Minas Gerais, Brazil, habitus, ventral view. Scale bar = 5 cm.