Oligoxystre diamantinensis, Bertani & Santos & Righi, 2009

Bertani, Rogerio, Santos, Thiago & Righi, Alexandre, 2009, A new species of Oligoxystre Vellard 1924 (Araneae, Theraphosidae) from Brazil, ZooKeys 5 (5), pp. 41-51 : 44-50

Oligoxystre diamantinensis sp. n.

urn:lsid:zoobank.org:act:C9FB2DF9-6B7B-45B0-BF56-E95FA05F6DB8

Figures 1-9

Type material. Holotype: male: Brazil, Minas Gerais, Diamantina , 18°13’57.2”S 43°35’14.9”W, 04.XII.2005, T. dos Santos & A. F. Righi ( MZSP 29071 ).

Paratypes: male ( MZSP 29072) and female ( MZSP 29073) same data and collectors.

Other material examined. Oligoxystre bolivianum , 1 male, Brazil, State of Mato Grosso, Chapada dos Guimarães 15°27’S 55°44’W, 19 March 1992, D. Pinz ( IBSP 9495 ), 1 female, February 1991, S.M. Lucas ( IBSP 9504 ) ; O. caatinga , 1 male, Brazil, State of Piaui, Parnaiba 2°54’S 4’°45’W, November 1994, R. Bertani ( IBSP 9499 ), 1 female, same data ( IBSP 9473 ) ; O. dominguense , 1 male (holotype), Brazil, state of Goiás, São Domingos 13°23’S 46°19’W, April 2000, A. Chagas Junior & M.G. Bichuettte ( IBSP 8625 ), 1 female (paratype) Minaçú, Serra da Mesa 13°49’S 48°18’W ( IBSP 9467 ) ; O. rufoniger , 1 male, Brazil, state of Bahia, Palmeiras, Parque Nacional da Chapada Diamantina, 12°28’070”S 41°25’175”W, inside bromeliads, 15 February 2008, R. Bertani, C.S. Fukushima e R.H. Nagahama ( MZSP 29101 ), 1 female (paratype), Central , Toca da Esperança 11°08’S 42°06’W, July 2000, A.D. Brescovit et al. ( IBSP 8553 ) ; O. tucuruiense , 1 male (holotype), Brazil, State of Pará, Tucuruí 3°45’S 49°40’W ( IBSP 9459 ), 1 female (paratype), 01 July 1984, C. Pantoja & R. S. Pereira ( IBSP 7936 ) .

Diagnosis. Male of O. diamantinensis sp. n. can be distinguished from O. bolivianum and O. dominguense by the absence of a small subapical keel on the male palpal bulb embolus ( Figs1-3 ); from O. caatinga by the embolus being shorter than 2.5 times the tegulum length ( Figs 1-3 ); from O. tucuruiense , O. rufoniger and O. auratum by the tibial spur being inserted in a perpendicular angle in relation to the tibia axis ( Figs.

4-5). Female can be distinguished from O. bolivianum by the spermathecae being much more longer than wide; from O. dominguense , O. rufoniger and O. tucuruiense by the absence of lateral lobes in the spermathecae; and from O. caatinga by the spermathecae having a large terminal lobe with five smaller lobes around it ( Fig. 6 ), instead of several small lobes. Additionally, males and females can be distinguished by the general blue metallic color pattern and the reddish setae on the abdomen ( Figs 7-8 ), instead of the general browish to reddish pattern shown by the other species. The metallic blue color is not lost in specimens preserved in alcohol, indicating its origen to be structural instead of due to the presence of biological pigments.

Etymology. Named after the type-locality, the city of Diamantina, in the state of Minas Gerais, Brazil.

Description. Male (holotype)( Figs 1-5 , 7 ): Total length with chelicerae: 25.5. Carapace: length 9.3, width 8.6. Abdomen: length 11.2, width 6.4. Eye tubercle low, length 1.1, width 2.0. Labium: length 0.8, width 1.5. Sternum: length 4.6, width: 3.7. Cephalic region low, hardly distinct. Thoracic striae undistinguishable. Fovea short, deep, straight. Chelicerae without rastellum, basal segments with 9 teeth. Clypeus absent. Anterior eye row procurved, posterior slightly recurved. AME round, diameter 0.35, 0.39 apart; ALE elliptical, 0.44 x 0.26, 1.07 apart. Posterior eye row slightly recurved; PME ovoid, 0.28 x 0.23, 0.78 apart; PLE ovoid, 0.39 x 0.18, 1.39 apart. Labium with 8 cuspules. Maxilla subrectangular, anterior lobe distinctly produced into conical process, inner angle bearing 25 cuspules. Sigilla on sternum undistinguishable. PMS one-segmented, 1.0 in length; PLS three-segmented, basal segment 2.28, median 1.87, apical 2.54. Claw tufts present; STC without teeth. Tarsi I-IV scopulate, IV with sparse row of setae; metatarsus I scopulate along a third of segment length, II 4/5 of its length, III 3/5 and IV 2/5 of their lengths. Femur IV without retrolateral scopula. Stridulatory setae absent. Length of legs and palp in Table 1 . Spines: tarsi lacking spines. Palpal femur p0-0-1, patella 0, tibia p1-2-1; legs I femur p0-0-1, patella 0, tibia v 2-2-2(1ap), metatarsus v1-0-0; II femur p0-0-1, patella 0, tibia v1-2-3(2ap), p1-0-1, metatarsus v1-0-0; III femur p0-1-1, r0-2-2, patella 0; tibia v3-3-2ap, p1-0-1, r1-0-1, metatarsus v0-2-3ap, p1-0-1, r1-0-1; IV femur p0-0-1, r0-1-2, patella 0, tibia v3-3-2ap, p1-0-1, r2-0-1, metatarsus v1-3-3ap, p1-0-1, r0-1-1. Male tibial spur small, with two branches slightly curved, originating from common, raised base ( Figs 4-5 ). Retrolateral branch longer than prolateral. Spur branches inserted in a perpendicular angle in relation to the tibia axis ( Fig. 5 ). Distance from tibia apex and the spur basis a quarter of the tibia length ( Fig. 4 ). Metatarsus I slightly bent at basal portion, passing laterally the retrolateral branch of tibial spur when flexed. Male palpal bulb with short subtegulum, not extending down bulb. Bulb globose, embolus long, 2.4 times longer than the tegulum, tapering to the tip and with a slight curvature on its distal quarter region ( Figs 1-3 ). Male palpal bulb keels absent. Urticating hairs absent. General color pattern of tegument golden-brown. Carapace, chelicerae, abdomen and legs covered dorsally and ventrally with metallic blue setae. Leg rings and longitudinal stripes on the patellae and tibiae hardly distinct. Abdomen covered with abundant long red setae and some short metallic blue setae. Anterior region with a stripe of red setae ( Fig. 7 ).

Female (Paratype)( Figs 6 , 8 ): Total length with chelicerae: 37.6. Carapace: length 10.9, width 9.9. Abdomen: length 19.8, width: 11.9. Eye tubercle: length 1.4, width 2.0. Labium: length 1.1, width 1.9. Sternum: length 5.2, width: 4.6. Cephalic region slightly elevated. AME round, diameter 0.36, 0.29 apart; ALE elliptical, 0.52 x 0.32, 1.23 apart. Posterior eye row slightly recurved; PME ovoid, 0.46 x 0.32, 0.92 apart; PLE ovoid, 0.41 x 0.24, 1.43 apart. Labium with 6 cuspules. PMS one-segmented, 1.52 in length; PLS three-segmented, basal segment 2.89, median 1.89, apical 2.99. All other characters as in male, except: metatarsi I and II scopulate along the full length of the segment, III 7/10 and IV 2/5 of their lengths. Length of legs and palp in Table 2. Spines: tarsi lacking spines. Palpal femur p0-0-1, patella 0, tibia v2-1-4ap, p0-1-0; legs I femur p0-0-1, patella 0, tibia v1-1-2ap, p1-0-1, metatarsus 0; II femur p0-0-2, patella 0, tibia v2-0-1ap, p1-1-0, metatarsus v1-0-0; III femur p0-0-2, r0-0-1, patella 0; tibia v1-2-2ap, p1-1-0, r1-1-0, metatarsus v2-0-4ap, p1-0-1, r1-0-1; IV femur r0-0-1, patella 0, tibia v1-3-3(2ap), p1-0-0, r1-0-1, metatarsus v0-4-3ap, p1-0-1, r1-0-1. Two spermathecae weakly sclerotized, long, ending in a large terminal lobe, two smaller lobes on the external region and three tiny lobes on the internal region, all them closely positioned ( Fig. 6 ). Color pattern as in male ( Fig. 8 ).

Variation (Male paratype). Length of legs and palp in Table 3. Spines: tarsi lacking spines. Palpal femur p0-1-1, patella 0, tibia p0-2-2; legs I femur p0-0-1, patella 0, tibia v 1-1-1ap, p 1-1-0, r 1-1-0, metatarsus v1-0-0; II femur p0-1-1, patella 0, tibia v1-1 -2ap, p1-1-0, metatarsus v1-0-0; III femur p1-1-1, r0-2-1, patella 0; tibia v1-3-2ap, p1-1-0, r1-1-0, metatarsus v3-0-4ap, p1-1-1, r0-1-1; IV femur p0-0-1, r0-2-1, patella 0, tibia v2-3-2ap, p1-1-0, r1-1-0, metatarsus v1-2-4ap, p1-0-1, r1-0-1.

Relationship. The cladogram proposed by Guadanucci (2003) and partially reproduced in Fig.9 shows Oligoxystre as a monophyletic genus sister to the clade Pterinochilus sp. ( Avicularia avicularia (Linnaeus, 1758) ( Euathlus vulpinus (Karsch, 1880) + Vitalius vellutinus (Mello-Leitão, 1923)) united by three non-exclusive synapomorphies (node A): few cuspules on the maxillae (character 1) (homoplasy shared with Catumiri spp.), few cuspules on the labium (character 2) (homoplasy shared with Ischnocolus algericus Thorell, 1875 + Catumiri spp. and Euathlus vulpinus ), and the labium wider than long (character 3) (homoplasy shared with Ischnocolus algericus + Catumiri spp.). Oligoxystre is divided into two fully dichotomous clades. One of the clades (node B) has the monophyletic group O. tucuruiense + O. rufoniger defined by a homoplasious apomorphy, the presence of lateral lobes in the spermatheca (character 4) (shared with Euathlus vulpinus ). The other clade has the monophyletic group O. bolivianum + O. dominguense (node D) sharing the presence of keels in the male palpal bulb embolus (character 6) as a synapomorphy. The sister-group of this clade (node C) is O. caatinga which shares with O. bolivianum + O. dominguense and other external taxa ( Sickius longibulbi Soares & Camargo, 1948 ( Ischnocolus algericus + Catumiri spp.)) the presence of a short clypeus (character 5). Oligoxystre diamantinensis sp. n. exhibits the three generic synapomorphies (characters 1-3), but the female lacks the lateral lobe in the spermatheca (character 4) and the male does not have keels in the embolus (character 6). Furthermore, both male and female lack a clypeus (plesiomorphic state for character 5). Thus, the new species lack all the apomorphies for the two clades and possibly would be in a basal trichotomy in that cladogram (indicated by an arrow in Fig. 9 ).

Concerning O. auratum, Vellard (1924) presented a detailed description of the species which allows to distinguish it from O. diamantinensis sp. n. Oligoxystre auratum has an overall browinsh pattern whereas the new species has a blue mettalic color ( Figs 7-8 ). The O. auratum tibial spur illustration ( Vellard 1924: 152, pl. 10 Fig. 38d) shows the branches in a parallel position with the tibia axis whereas in O. diamantinensis sp. n. the tibial spur branch axis is perpendicular in relation to the tibia axis ( Fig. 5 ).

Distribution. Only known from type locality.

Habitat description. The specimens were found in “campo rupestre” areas (Figs 10-11), characterized by its height above sea level – above 900m, in association with a high degree of outcropping and consequent reduction of soil depth (Giulietti and Pirani 1988). The vegetation in the area of occurrence of O. diamantinensis sp. n. have predominantly specimens of the families Asteracea, Melastomatacea, Gramineae, Cyperacea, Cactacea , Eicaceae, Leguminosacea, Velloziaceae, Eriocaulacea and Xyridacea ( Silva et al. 2005) .The climate is tropical – temperature ranging from 18 to 20°C, minimum 4°C in June/July reaching 35°C by December/January ( Silva et al. 2005). The rainy season extends from November to March (precipitation mean 223.19 mm). In the dry season from June to August the pluviosity mean falls to about 8.25 mm ( Silva et al. 2005). The relative humidity varies between 72.33% and 89.75% (for

2001 and 1995, respectively) (Silva, et al. 2005). The three collected specimens were found in altitudes about 1.250m a.s.l, always in rocky places, either inside crevices or under large stones where they normally build silky tunnels.

Figures

Figs 1-6.Oligoxystre diamantinensis sp. n. holotype male 1. left male palpal bulb, prolateral view; 2. left male palpal bulb, retrolateral view; 3. left palp, retrolateral view; 4. left leg I spur, ventral view; 5. Left leg I spur, prolateral view; Paratype female 6. spermathecae, dorsal view. Scale bar: 1 mm.

Figs 7-8.Oligoxystre diamantinensis sp. n. 7. holotype male; 8. paratype female. Photos: 7 Alexandre Righi; 8 Rogério Bertani.

Fig. 9. Part of Guadanucci’s (2003) cladogram showing Oligoxystre species relationship. Characters: 1 few cuspules on the maxillae; 2 few cuspules on labium; 3 labium wider than long; 4 spermathecal lateral lobe present; 5 clypeus narrow; 6 keel on male palpal bulb embolus present; 6 spermatheca as long as wide. Black square = synapomorphy. White square = homoplasy. The arrow indicates the probable position of Oligoxystre diamantinensis sp. n. in the cladogram.

Tables

Table 1. Oligoxystre diamantinensis sp. n. Male Holotype. Length of left legs and palpal segments.

	Palp	I	II	III	IV
Tarsi	1.9	4.4	4.3	4.0	4.5
Metatarsi	---	7.6	7.3	7.1	10.2
Tibiae	4.8	7.7	6.9	6.3	8.5
Patellae	3.8	5.1	5.0	4.1	4.5
Femora	5.9	9.4	9.0	8.1	9.9
Total	16.4	34.2	32.5	29.6	37.6

Table 1. Oligoxystre diamantinensis sp. n. Male Holotype. Length of left legs and palpal segments.