Metagonia diamantina, Machado & Ferreira & Brescovit, 2011

Machado, On. O., Ferreira, Rodrigo L. & Brescovit, Io. D., 2011, A new troglomorphic Metagonia Simon 1893 (Araneae, Pholcidae) from Brazil, Zootaxa 3135 (1), pp. 59-62 : 59-62

Metagonia diamantina new species

( Figures 1–11 )

Type material. Male holotype and paratype female from Lapa do Bode cave (12º56'02"S; 41º03'44"W), Itaeté, Bahia, Brazil, 26.VII.2007, R. L. Ferreira col., deposited in ISLA 1429 and ISLA 1428, respectively .

Etymology. The specific name is a noun in apposition taken from the Chapada Diamantina, a famous Brazilian region where the cave is located.

Diagnosis. The species is compared with the other three eyeless Metagonia species. Metagonia diamantina can be distinguished from M. bellavista and M. debrasi by the unpaired apophysis on the male clypeus ( Figs. 4 , 10 ) and the epigynal scape ( Figs. 7–8 ), and from M. reederi by the long, divided and strong procursus ( Fig. 3 ), the smooth chelicerae ( Fig. 5 ) and the epigynal scape ( Figs. 7–8 ).

Description. Male (Holotype). Total length 1.8, carapace length 0.7, width 0.7, leg I 13.3 (3.3 + 0.4 + 3.6 + 5.0 + 1.1), tibia II 2.5, tibia III 1.8, tibia IV 2.3; tibia I l/d 40. Habitus as in figures 9–10. Carapace slightly indented medially but without thoracic groove ( Fig. 9 ), homogeneous pale yellow without stripes or spots ( Figs. 9–10 ), almost depigmented. Ocular area undifferentiated, eyeless, without lens or ocular pigmentation. Clypeus with a simple pointed apophysis ( Figs. 4–5 ). Sternum pale yellow. Chelicerae pale yellow, without apophyses or modified hairs ( Fig. 5 ). Palps ( Figs. 1–3 ) pale yellow; femur without apophysis; trochanter with strong ventral apophysis; procursus divided distally, hinged process elongated and strong ( Fig. 3 ), general color pale yellow, darkening to dark brown on the tips; bulb simple with a slender embolus ( Fig. 2 ). Legs pale yellow, spines absent, retrolateral trichobothrium of tibia I at 6%, tarsus I with approximately 18 pseudosegments. Abdomen globular ( Figs. 9–10 ), completely pale yellow, genital plate indistinct.

Female (paratype). Total length 2.5, carapace length 0.8, width 0.9, leg I 14.3 (3.8 + 0.4 + 3.7 + 5.3 + 1.1), tibia II and III missing, tibia IV 3.6. In general very similar to male, eyeless and without clypeus modification ( Fig. 6 ). Habitus as in fig. 11. Epigynum pale yellow, the epigynal plate with distinct scape ( Figs. 7 ). Internal genitalia with a complex system of asymmetrical, sclerotized ducts ( Fig. 8 ).

Distribution. Known only from the type locality.

Other material examined. None.

Remarks. The species probably belongs to Huber (2000) ’s ‘group 4’. It shows similarities to M. lancetilla Huber 1998 , sharing the long hinged process and the epigynal scape (very small in M. lancetilla ).

Habitat description and natural history. The two specimens were collected in an inner portion of the Lapa do Bode cave (approximately 200 meters from the nearest entrance), in a chamber with moist soil and some bat guano piles. The specimens were moving slowly on the cave floor, and they were found at least 40 meters apart from each other. The potential preys observed in the cave were mainly springtails ( Arrhopalitidae and Cyphoderidae , both troglomorphic).

The Lapa do Bode cave has 1,430 meters of horizontal projection, with conduits of anastomotic pattern. Although the cave is mainly dry, the existence of some water ponds in some inner areas enhances the moisture content in the cave atmosphere (in some parts of the cave the moisture content is 100%). The temperature inside the cave is around 24.5ºC. The cave is currently being used for touristic purposes, and the area where the spiders were found is visited. Although these activities are not apparently altering intensively the cave (there are no electric lights), there is concern that the touristic activities could have an impact on the species.

Figures

FIGURES 1–8. Metagonia diamantina n. sp. 1. Male palp, retrolateral; 2–3. Bulb and procursus, 2. Prolateral, 3.Dorsal; 4–5. Male carapace, 4. Anterolateral, 5, Frontal; 6. Female carapace, frontal; 7–8. Epigynum, 7. Ventral, 8. Dorsal. Arrows indicate hinged process. Scale bars: 0,25 mm.

FIGURES 9–11. Metagonia diamantina n. sp. 9–10. Male. 9. Dorsal, 10. Lateral; 11. Female, lateral. Scale bars: 0,5 mm.