Munduruku , a new Theraphosid genus from Oriental Amazonia ( Araneae , Mygalomorphae )

Munduruku gen. nov. is proposed for the type species Munduruku bicoloratum sp. nov., from Juruti and Santarém, Pará, Brazil. The main diagnostic character of Munduruku gen. nov. is the presence of a subapical, lanceolate keel on the male palpal bulb, which is unique among the basal taxa of Theraphosinae with type III-IV urticating setae. The female spermathecae consist of two spheroid receptacles with funnel-shaped necks, each of which bears a sclerotized area. In both sexes, the abdomen is remarkably patterned, an uncommon feature in adults of New World theraphosids. Both the bulbus lanceolate keel and the abdominal color pattern are hypothesized as synapomorphies of the genus.

Theraphosidae harbors the largest spiders in the world and constitutes the most speciose family of the infraorder Mygalomorphae, with 946 species in 124 genera (Platnick, 2013).They are distributed mainly in the Neotropical, Ethiopian, Oriental and Australian regions, with a few species in southern Europe.About half of the known species inhabit the Neotropics, most of them included in the Theraphosinae, endemic to this region.Due to the homogeneity of theraphosinae morphology, and consequently the scarcity of taxonomic characters, great confusion has reigned in the classification of the group (Schiapelli & Gerschman, 1979;Valerio, 1980;Minch, 1989;Raven, 1990;Pérez-Miles et al., 1996;Bertani, 2000;Perdomo et al., 2009).More recent scientific contributions improved the tools for species recognition, for cladistic studies, and also for taxa discovery.Among these contributions, Bertani (2000) made an important study of homology of keels on male palpal bulb, which now constitute key features in Theraphosinae taxonomy.The presence of keels and an extended subtegulum on the male palpal bulb (Raven, 1985), together with theraphosinae urticating setae, were considered the main synapomorphies for the subfamily (Pérez-Miles et al., 1996).
A parcel of tarantula specimens, representing a single species, recently collected in the Oriental Amazonia (Pará, Brazil), share the synapomorphies of Theraphosinae, but did not fit any of the known genera.They have type III (males) and types III, IV (females) urticating setae, but differ from all basal Theraphosinae with these types of urticating setae by the presence of a lanceolate subapical keel on the male palpal bulb and by the presence of an unusual dorsal pattern on the abdomen, composed of a wide longitudinal dark brown band with several lateral extensions.These two characters are here considered as putative synapomorphies of an undescribed lineage.Consequently, we propose Munduruku gen.nov., which is diagnosed, described and figured on the basis of the type species, Munduruku bicoloratum sp.nov.

Munduruku gen. nov.
Type species: Munduruku bicoloratum sp.nov.Etymology: Munduruku is a noun in apposition from the Munduruku (a language of the Tupi linguistic trunk) and is the name of an indigenous tribe which inhabited the region of Juruti, the typical locality of the type species of the genus; the gender is neuter.
Diagnosis.Differ from the majority of theraphosinae genera by the presence of type III (male) and III, IV (female) urticating setae and by the presence of a patterned abdomen (Figs 2-4); from Cyriocosmus Simon, 1903 and Hapalopus Ausserer, 1875, the only other theraphosinae genera with patterned abdomens, in the shape of the abdominal pattern and in the general morphology of the male palp and female spermathecae, especially the absence of a paraembolic apophysis on the male palp; from all genera with similar urticating setae patterns, by the presence of a SAK (Figs 6, 13) on the male palpal bulb.In addition to the presence of abdominal pattern and SAK, they also differ from Plesiopelma Pocock, 1901 in the absence of a basal process on the male metatarsus I and in the morphology of the double tibial apophysis, with fused bases and convergent branches (Figs 5,14).
Affinities.Munduruku gen.nov.resembles Plesiopelma in the presence of type III and IV urticating hairs, and in the general pattern of male palpal organ morphology, but differs from that genus in the size and morphology of the palpal organ, which presents a distinct SAK (Figs 6, 13).In Plesiopelma, males have a small, subapical tooth which is an extension of the PIK, while in Munduruku gen.nov.this structure is a separate keel, as in Vitalius Lucas, Silva Junior & Bertani, 1993 andNhandu Lucas, 1981 (genera which lack type IV urticating setae, having types I and III instead).The new genus also differ from Plesiopelma in the absence of a basal process on the male metatarsus I and in the morphology of the male tibial apophysis on leg I (Figs 5, 14).Also, the female spermathecal receptacles are not twisted.Females of Munduruku gen.nov.present spermathecae with two spheroid distal receptacles, with a straight funnel-shaped neck bearing a sclerotized area (Fig. 8).Males and females also differ from those of Plesiopelma species by the presence of a singularly shaped abdominal pattern (Figs 2-4).In this regard, Munduruku gen.nov.resembles Cyriocosmus and Hapalopus, but the pattern is different and our specimens do not belong to either of these genera, as indicated by several characters, including genital morphology in both sexes.
Given the absence of a phylogenetic framework for Theraphosinae, an alternative course of action would be to consider the species described below as an additional species of Plesiopelma.This would avoid the proposition of another monotypic genus in a complex nov. in Plesioplema would bring far more problems than solutions.From a strictly operational point of view, this decision would broaden the diagnosis of the genus to an unworkable level.From a phylogenetic point of view, including M. bicoloratum sp.nov. in Plesiopelma would probably turn this taxon into a non-monophyletic group, since the species here described do not share any of the characters presently considered as putative synapomorphies of Plesiopelma, such as the conspicuous metatarsal process.On the other hand, the unique combination of characters presented by Munduruku bicoloratum sp.nov., including two exclusive characters that may be regarded as potential synapomorphies, is strong evidence that this species belongs to a lineage of its on.Description.See description of the type species.
Natural History.Most of the specimens from Canaã and Juruti were collected in pitfall traps used for herpetological survey.Some specimens from Juruti were collected by manual search at night (MPEG 19029) and from a project of wildlife rescue (MPEG 19030).