29.11.2021

Theraphosinae sp. "Piura" = Thrixopelma pruriens Schmidt, 1998

Recently we could occasionally read in various Facebook groups the the assumption that Theraphosinae sp. "Piura" possibly belongs to Thrixopelma pruriens Schmidt, 1998. In response to a posting by Karin Hildebrandt on 11/28/2021 regarding various tarantula new additions to our collection, this discussion came up again. Internationally known Arachnologists like Rick West and Dr. Rogerio Bertani expressed their thoughts on the subject there, but could not contribute to the clarification of the facts. Due to lack of preserved material an adult, living Theraphosinae sp. "Piura" male as well as an adult, living Thrixopelma pruriens male were anesthetized today and their bulbi were photographed in comparative position. Also two spermathecae of the mentioned forms from our archive were compared to get closer to the answer to a possible conspecificity of both hobby forms.

Unfortunately not much is known about the taxonomic characteristics of Thrixopelma pruriens. In the most recent work on this [see Sherwood et al. (2021)] there are unfortunately only a few illustrations and mentions of useful - mainly genital morphological - characters, which we have used as a guide.

Comparison of the bulbi of both males (Pic 1 = Thri. pruriens; Pic 2 = Ther. sp. "Piura") shows very high agreement. Both bulbi have a similar pronounced "Prolateral inferior keel" (PI) which shows an identical course. Also the "Tegular heel" (TH) is pronounced in the same way. The embolus tip is similar in shape and rather short and broad in both bulbi. Both bulbi also show a high structural similarity to the illustrated Thrixopelma pruriens bulbus in the above mentioned publication by Sherwood et al. (Pic 5).

Likewise, the shape of the spermathecae of Thrixopelma pruriens (Pic 4) and Theraphosinae sp. "Priura" (Pic 3) is nearly identical, which may be taken as further evidence of conspecificity. A comparison with the illustrated spermathecae to Thrixopelma pruriens in Sherwood et al. (Pic 6) shows also here a very strong agreement of the spermathecal forms.

Resumé:

We assume that the Spiders referred to as Theraphosinae sp. "Piura" in the community are most likely Thrixopelma pruriens Schmidt, 1998, based on the high structural similarity with respect to genital morphology. A 100% certainty about the conspecificity would probably be provided by a DNA comparison of the two forms or a scientifically supervised hybridization attempt. In the meantime, the actual affiliation of Theraphosinae sp. "Piura" to Thrixopelma pruriens could be confirmed by the detailed scientific examination of adult males -> HERE!

Reference:

Sherwood, D., Gabriel, R., Kaderka, R., Lucas, S. M. & Brescovit, A. D. (2021). Stabilizing a chaotic taxonomy: redescription and redefinition of the genera Lasiodorides Schmidt & Bischoff, 1997 and Thrixopelma Schmidt, 1994 (Araneae: Theraphosidae). Arachnology 18(8): 893-917.