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Thrixopelma sp. “Cusco” finally has a scientific name: Thrixopelma kimraykawsaki Signorotto et al. 2025
In March of this year, a description of a new Thrixopelma species from Cusco in Peru was published in the journal ARACHNOLOGY. We immediately suspected that it could be the species that is known in the tarantula community first as Theraphosinae sp. “Cusco” and after our identification work (see here) as Thrixopelma sp. “Cusco” (Pic. 1). We immediately began to re-examine the two preserved males of this species in our collection and to compare them with the description of the new species.
The result of this investigation was a pretty clear confirmation of our hypothesis. The males of the tarantula species previously known as Thrixopelma sp. “Cusco” that we examined in our collection showed that this species matches the characters of the new Thrixopelma kimraykawsaki.
First, we compared the structure of the bulbs and their keels. Since the bulbs of our males were very dark, we bleached one of our males' bulbs for 8 hours in hydrogen peroxide using the method of von Wirth & Hildebrandt (2022) to better illustrate the structure and shape of the keels. The keels and the structure of the bulb are almost identical in all positions (Pic. 2) to the figures in the original description (Pic. 3). Only in the ventral position can you see that the PS in one of our males bends slightly. However, the shape of this keel in the other male is similar to the figure in the original work (Pic. 4). This slight change is due to the interspecific variation in the shape of the keels.
Furthermore, the structure of the tibial apophyses and in particular the spination of the two apohysis of our males (Pic. 5) is identical to the illustrations in the original description of Thrixopelma kimraykawsaki (Pic. 6).
Also, the distribution and approximate number of labial cuspules on our males (Pic. 7) almost match those on the male of Thrixopelma kimraykawsaki (Pic. 8 ).
The female described in the description of Thrixopelma kimraykawsaki as a paratype seems to be still very young with a body length of 3.4 cm, because older adult females of Thrixopelma sp. “Cusco” in the tarantula community are significantly larger. In addition, the described holotype male of Thr. kimraykawsaki is also quite a bit larger than the female paratype. Among other things, the wide distance of the receptacula seminis to each other is mentioned in the paper as a diagnostic character for the differentiation of the females of this new Thrixopelma species from the females of other Thrixopelma species. Pic. 9 shows the development of the spermatheca of a female Thrixopelma sp. “Cusco” in our collection with a body length of 3 cm, which almost matches the body length of the female paratype of Thr. kimraykawsaki. Here, also, the two receptacula seminis are far apart and structurally very similar to the illustration of the spermatheca in the original description (Pic 10). The same female with a body length of 4 cm no longer shows the receptacula seminis so far apart from each other and the structure and size of the receptacula seminis is now also different. At a body length of 6 cm, the distance between the receptacula seminis is again significantly smaller and they are even larger. Based on our experience in the photographic documentation of the development of thousands of tarantula spermathecae in all nymph and adult stages, we would like to point out here that the shape of the spermathecae changes slightly within a species and with each further individual moult. According to our findings, distances and the fine structure of the receptacula seminis can hardly be used to distinguish between species. Only the general shape of these structures can provide hints for a phylogenetic signal.
Resumé:
The taxonomic examination of two Thrixopelma sp. “Cusco” males in our collection revealed a high degree of similarity with the recently described new species Thrixopelma kimraykawsaki from Cusco (Peru) in terms of the taxonomically useful characters of males and females. For this reason, we conclude that the Thrixopelma sp. “Cusco” known in the tarantula community (still known to some backward tarantula keepers by the very old name “Theraphosinae sp. Cusco”) is a Thrixopelma kimraykawsaki.
Reference:
Signorotto, F., Ferretti, N., Chaparro, J. C. & Ochoa, J. A. (2025). The genus Thrixopelma Schmidt, 1994 from Peru: redescription of the male of T. ockerti Schmidt, 1994 (Araneae: Theraphosidae: Theraphosinae), and a new species. Arachnology 20(1): 107-114.
von Wirth, V. & K. Hildebrandt (2022). Bleaching of taxonomically important body structures in spiders using the example of tarantulas (Araneae: Theraphosidae). BTS Journal (37) 1, pp. 34-41
In March of this year, a description of a new Thrixopelma species from Cusco in Peru was published in the journal ARACHNOLOGY. We immediately suspected that it could be the species that is known in the tarantula community first as Theraphosinae sp. “Cusco” and after our identification work (see here) as Thrixopelma sp. “Cusco” (Pic. 1). We immediately began to re-examine the two preserved males of this species in our collection and to compare them with the description of the new species.
The result of this investigation was a pretty clear confirmation of our hypothesis. The males of the tarantula species previously known as Thrixopelma sp. “Cusco” that we examined in our collection showed that this species matches the characters of the new Thrixopelma kimraykawsaki.
First, we compared the structure of the bulbs and their keels. Since the bulbs of our males were very dark, we bleached one of our males' bulbs for 8 hours in hydrogen peroxide using the method of von Wirth & Hildebrandt (2022) to better illustrate the structure and shape of the keels. The keels and the structure of the bulb are almost identical in all positions (Pic. 2) to the figures in the original description (Pic. 3). Only in the ventral position can you see that the PS in one of our males bends slightly. However, the shape of this keel in the other male is similar to the figure in the original work (Pic. 4). This slight change is due to the interspecific variation in the shape of the keels.
Furthermore, the structure of the tibial apophyses and in particular the spination of the two apohysis of our males (Pic. 5) is identical to the illustrations in the original description of Thrixopelma kimraykawsaki (Pic. 6).
Also, the distribution and approximate number of labial cuspules on our males (Pic. 7) almost match those on the male of Thrixopelma kimraykawsaki (Pic. 8 ).
The female described in the description of Thrixopelma kimraykawsaki as a paratype seems to be still very young with a body length of 3.4 cm, because older adult females of Thrixopelma sp. “Cusco” in the tarantula community are significantly larger. In addition, the described holotype male of Thr. kimraykawsaki is also quite a bit larger than the female paratype. Among other things, the wide distance of the receptacula seminis to each other is mentioned in the paper as a diagnostic character for the differentiation of the females of this new Thrixopelma species from the females of other Thrixopelma species. Pic. 9 shows the development of the spermatheca of a female Thrixopelma sp. “Cusco” in our collection with a body length of 3 cm, which almost matches the body length of the female paratype of Thr. kimraykawsaki. Here, also, the two receptacula seminis are far apart and structurally very similar to the illustration of the spermatheca in the original description (Pic 10). The same female with a body length of 4 cm no longer shows the receptacula seminis so far apart from each other and the structure and size of the receptacula seminis is now also different. At a body length of 6 cm, the distance between the receptacula seminis is again significantly smaller and they are even larger. Based on our experience in the photographic documentation of the development of thousands of tarantula spermathecae in all nymph and adult stages, we would like to point out here that the shape of the spermathecae changes slightly within a species and with each further individual moult. According to our findings, distances and the fine structure of the receptacula seminis can hardly be used to distinguish between species. Only the general shape of these structures can provide hints for a phylogenetic signal.
Resumé:
The taxonomic examination of two Thrixopelma sp. “Cusco” males in our collection revealed a high degree of similarity with the recently described new species Thrixopelma kimraykawsaki from Cusco (Peru) in terms of the taxonomically useful characters of males and females. For this reason, we conclude that the Thrixopelma sp. “Cusco” known in the tarantula community (still known to some backward tarantula keepers by the very old name “Theraphosinae sp. Cusco”) is a Thrixopelma kimraykawsaki.
Reference:
Signorotto, F., Ferretti, N., Chaparro, J. C. & Ochoa, J. A. (2025). The genus Thrixopelma Schmidt, 1994 from Peru: redescription of the male of T. ockerti Schmidt, 1994 (Araneae: Theraphosidae: Theraphosinae), and a new species. Arachnology 20(1): 107-114.
von Wirth, V. & K. Hildebrandt (2022). Bleaching of taxonomically important body structures in spiders using the example of tarantulas (Araneae: Theraphosidae). BTS Journal (37) 1, pp. 34-41
