07.10.2022

Euathlus sp. "blue" is Euathlus truculentus L. Koch 1875

At the tarantula exchange in Weinstadt (Germany) we received an exuvia of a spider from Fernando Rivas, which he received as "Euathlus sp. "blue"". He asked us to find out which species it is.

Because of the presence of urticating hairs of type III and IV (Pic 1) it was clear that it must be a Theraphosinae. The shape of the spermatheca with its two divergent receptacles and with its lateral spheroid chamber (Pic 2) in combination with the urticating hair type IV and the spines on the entire palpentibia ventrally (Pic  3) as well as the sternum that is clearly longer than wide (Pic 4) indicated a Euathlus species (see Perafán & Pérez-Miles 2014).

After comparing the characteristics of the present exuvium with those of Euathlus species, it was quickly clear that this species offered as Euathlus sp. "blue" was in fact Euathlus truculentus L.Koch 1875 because of the follwing reasons:

The shape of the spermatheca in Pic 2 is nearly identical with the spermathecae of the synonyms of this species [compare Pic 5 from Schmidt 1991 to Paraphysa pulcherimaklaasi (red arrow) and Paraphysa pryxotrichoides (green arrow) = both synonyms of Euathlus truculentus]. Also the spermatheca of the examined exuvia resembles the spermatheca shown in Schiapelli & Gerschman 1963 as belonging to "Paraphysa manicata" (Pic 6). However, this is a wrongly identified Specimen, which actually does not belong to the present Euathlus manicata, but to Euathlus truculentus. Also the drawing of the sternum of this false "manicata" female, shown in Schiapelli & Gerschman 1963, resembles the sternum shape in the examined exuvia (Pic 7). Perafán & Pérez-Miles, in their work in 2014 for Euathlus truculentus, also indicated only a small number of labium cuspules (<20). Although the labium of the exuvium has 23 cuspules (Pic 8 ), this is only slightly above the value reported for E. truculentus. Usually, the number of cuspules on the labium is subject to some minor variation and thus this feature of the exuvium also speaks for the species truculentus.

Resumé:

The Euathlus sp. "blue" present and kept in the tarantula community can probably be assigned to the species Euathlus truculentus L. Koch 1875 in the vast majority of cases.*1

*1= Steffen Esche has informed us that he already pointed out 3 years ago in a posting on Arachnoboards that Euathlus sp. "blue" is conspecific to Euathlus truculentus. So the result of our actual investigation should be known in the community for a long time.

Reference:

Perafán, C. & Pérez-Miles, F. (2014). The Andean tarantulas Euathlus Ausserer, 1875, Paraphysa Simon, 1892 and Phrixotrichus Simon, 1889 (Araneae: Theraphosidae): phylogenetic analysis, genera redefinition and new species descriptions. Journal of Natural History 48(39-40): 2389-2418.

Schiapelli, R. D. & Gerschman de P., B. S. (1963). Los géneros chilenos Phrixotrichus Simon, 1889 y Paraphysa Simon, 1892 (Theraphosidae, Araneae) en la Argentina. Nuevas citas de algunas arañas comunes a ambos paises. Revista de la Sociedad Entomológica Argentina 26: 103-108.

Schmidt, G. (1991). Eine neue Paraphysa-Art aus Equador (Araneida: Theraphosidae: Theraphosinae). Arachnologischer Anzeiger 20: 8-12.