Homoeomma Ausserer, 1871

Radan Kaderka, Tim Lüddecke, Milan Řezáč, Veronika Řezáčová & Martin Hüsser, 2023, Revision of the Peruvian tarantula Homoeomma peruvianum (Chamberlin, 1916): description of a new genus with eleven new species and insights to the evolution of montane tarantulas (Araneae: Theraphosidae: Theraphosinae), Journal of Natural History 57 (41 - 44), pp. 1710-1824 : 1723-1725

Genus Homoeomma Ausserer, 1871

Agathostola Simon, 1892 , type species Agathostola strabo Simon, 1892 , male holotype from Colombia in MNHP ( Gerschman de Pikelin and Schiapelli, 1972).

Calopelma Chamberlin, 1917 , type species Calopelma brasilianum Chamberlin, 1917 , male holotype from Brazil, Rio de Janeiro, in MCZ ( Gerschman de Pikelin and Schiapelli, 1972).

Cyclothoracoides Strand, 1929 , type species Cyclothoracoides cyclothorax (Mello-Leitão, 1923) , male from Brazil ( Lucas and Indicatti, 2015).

Butantania Mello-Leitão, 1935 , type species Butantania hirsuta Mello-Leitão, 1935 , male from Brazil, State of Rio de Janeiro, Itatyaia , in IBSP ( Pérez-Miles et al., 1996).

Type species

Homoeomma stradlingi O. Pickard-Cambridge, 1881 , female holotype from Bahía, Brazil, and two male paratypes from Brazil (in NHM, not examined).

Diagnosis

Homoeomma differs from all other Theraphosinae genera in the presence of subparallel PS and PI keel on embolus and digitiform basal apophysis (TA) on tegulum of male palpal bulb, in combination with abdominal urticating setae of type III+IV. Males of some species have a retrolateral basal nodule in metatarsus I, more or less developed. This structure is similar to that found in Plesiopelma Pocock, 1901 ( Pérez-Miles et al., 1996). Two unequal subapical apophyses are present on male tibia I, metatarsus I, when flexed touches both of them. Labium with numerous cuspules in apical third ( Gerschman de Pikelin and Schiapelli, 1973).

Distribution

Brazil, Argentina, Uruguay, Chile.

Remarks

The genus Homoeomma Ausserer, 1871 was established to accommodate Mygale versicolor C.L. Koch, 1842 , male and female from Rio de Janeiro, Brazil, collected by the Novara Expedition ( Ausserer, 1871; Gerschman de Pikelin and Schiapelli, 1972). Ausserer (1871) diagnosed Homoeomma by the almost congruent size of AME and PME. In a brief description he emphasised the following characters associated with this genus: cephalothorax is slightly longer than wide, moderately elevated, with deep and procurved thoracic fovea, eye tubercle is high, widely oval, lateral eyes are of the largest size, and AME and PME of almost congruent size, the distance between AME is greater than their diameter, labium is quadrangular and elevated, legs spinose, leg formula 4, 1, 2, 3, scopulae are thick but narrow, tibia IV is shorter than metatarsus IV, PLS as long as tarsus I ( Ausserer, 1871).

As Mygale versicolor C.L. Koch, 1842 was a different species to Mygale versicolor Walckenaer, 1837 from Guadeloupe and Martinique (today̾s Caribena versicolor (Walckenaer, 1837)) , and because the name was thus preoccupied, O. Pickard-Cambridge (1881) described Homoeomma stradlingi O. Pickard-Cambridge, 1881 based on the female holotype from Bahía, Brazil (type in NHM), and transferred two adult males of M. versicolor C.L. Koch, 1842 from his private collection to H. stradlingi (O. Pickard-Cambridge, 1881) . He believed that the mentioned female and both males of M. versicolor C.L. Koch, 1842 from Brazil belonged to the same species. However, in the bulb, which was figured by Pickard-Cambridge (1881), a digitiform basal apophysis on tegulum is missing which casts doubts on the placement of this species in Homoeomma . Pickard-Cambridge (1881) also synonymised Mygale versicolor C.L. Koch, 1842 from Rio de Janeiro, Brazil, with Homoeomma stradlingi from Bahía, Brazil ( Pickard-Cambridge, 1881), albeit it is unclear whether the type specimens of the two species were compared. It is presumable that H. stradlingi may represent a complex of species.

Later, although the male holotype of H. stradlingi had never been described or designated by Pickard-Cambridge (1881), Gerschman de Pikelin and Schiapelli (1972) examined male holotype no. 42–43 from NHM, perhaps one of the two males from Pickard-Cambridge̾s private collection, but the jar contained in total three males from Bahía, Brazil. Gerschman de Pikelin and Schiapelli (1972) figured male and female genitalia of known Homoeomma spp. for the first time, including male palpal bulb, palpal tibia and tibia I of H. stradlingi , and modified the generic diagnosis.

Pérez-Miles et al. (1996) also examined the male type of H. stradlingi from NHM. He diagnosed Homoeomma by the presence of a digitiform basal apophysis in male palpal bulbs. Some species may have a retrolateral basal nodule on metatarsi I, similar to that found in Plesiopelma ( Pérez-Miles et al., 1996) .

Bertani (2000) examined H. stradlingi from Téresopolis , Rio de Janeiro, Brazil ( IBSP 4683 ), and H. montanum from Paranapiacaba , São Paulo, Brazil ( IBSP 7045 ), and pointed out the presence of tegular apophysis and two almost parallel prolateral keels in male palpal bulb morphology. The apical keel is mentioned as absent in palpal bulb ( Bertani, 2000) .

Montenegro, Aguilera and Casanueva (2018) published a new diagnosis for Homoeomma : males have bulbs with tegular apophysis, the embolus shows an angle of 90° to 135° in relation to the axis of the bulb (except for Tmesiphantes ), and the metatarsus when flexed touches both branches of tibial apophysis. Females differ from other theraphosids in the shape of spermathecae, without constriction in the apex or granules ( Montenegro, Aguilera and Casanueva, 2018).

Revision of the type specimens of Homoeomma stradlingi O. Pickard-Cambridge, 1881 , Mygale nigrum Walckenaer, 1837 and Mygale versicolor C.L. Koch, 1842 is needed to stabilise the generic type of the genus Homoeomma .