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

[Theraphosid Research Team]

At the tarantula exchange before two weeks ago in Weinstadt (Germany) we got an exuvia of a spider from our friend and tarantula enthusiast 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 (Fig. 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 (Fig. 2) in combination with the urticating hair type IV and the spines on the entire palpentibia ventrally (Fig. 3) as well as the sternum that is clearly longer than wide (Fig. 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 Fig. 2 is nearly identical with the spermathecae of the synonyms of this species [compare Fig. 5 from Schmidt 1991 to Paraphysa pulcherimaklaasi (red arrow) and Paraphysa pryxotrichoides (green arrow) = both actual synonyms of Euathlus truculentus]. Also the spermatheca of the examined exuvia resembles the spermatheca shown in Schiapelli & Gerschman 1963 as belonging to female of "Paraphysa manicata" (Fig. 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 (Fig. 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 (Fig. 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.

CONCLUSIONS:
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 in this Forum here that Euathlus sp. "blue" is conspecific to Euathlus truculentus. So the result of our investigation should be known in the community for a long time, but this realization has apparently not yet spread everywhere in the hobby.

LITERATURE:
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.

 

[viper69]

This is a really good post. There are many species, especially out of Chile, assigned to this genus but with nothing more than a “sp XYZ” as they are not fully described.

At one point I found a website that had about 13 or so localities out of Chile.

I sure wish they would be scientifically described . Some of them are striking in color, and the low temperatures that they live in.

 

[AphonopelmaTX]

One can't discuss the Chilean species of tarantula without mentioning the excellent web site "Tarantulas of Chile" at https://tarantulas-chilenas.wixsite.com/home

After a review of the tarantulas that occur in the Valparaiso region (Region V) from that web site, I have a hard time identifying any tarantula as Euathlus truculentus with confidence since there are several different tarantulas that share similar palpal bulb and spermathecae morphology. Using the available descriptions that include illustrations of the male and female genitalia, one has to wonder how much intraspecific variation could occur.

Have a look through the page for the species specifically for the Valparaiso region. I count 4 species that could be Euathlus truculentus if one allows for variations the the shape of spermathecae and palpal bulbs. I'm not sure why the one with iridescent blue femurs is the one attributed to E. truculentus and not any of the others. Maybe I'm missing a few details.

REGION DE VALPARAISO | Tarantulas Chilenas

tarantulas-chilenas.wixsite.com

 

[Theraphosid Research Team]

One can't discuss the Chilean species of tarantula without mentioning the excellent web site "Tarantulas of Chile" at https://tarantulas-chilenas.wixsite.com/home

After a review of the tarantulas that occur in the Valparaiso region (Region V) from that web site, I have a hard time identifying any tarantula as Euathlus truculentus with confidence since there are several different tarantulas that share similar palpal bulb and spermathecae morphology. Using the available descriptions that include illustrations of the male and female genitalia, one has to wonder how much intraspecific variation could occur.

Have a look through the page for the species specifically for the Valparaiso region. I count 4 species that could be Euathlus truculentus if one allows for variations the the shape of spermathecae and palpal bulbs. I'm not sure why the one with iridescent blue femurs is the one attributed to E. truculentus and not any of the others. Maybe I'm missing a few details.

REGION DE VALPARAISO | Tarantulas Chilenas

tarantulas-chilenas.wixsite.com

I can understand your comment from the point of view of the purely morphological data on the mentioned page. However, the question arises whether the "forms" presented there, which seem to be almost identical to E. truculentus in terms of genital morphology, are in fact always different species, or - what I consider more likely - that they are merely local populations of Euathlus truculentus. It is remarkable that just the known different species like E. parvulus are morphologically easy and clear to separate from Euathlus truculentus. Beside the shape of the bulb and spermathecae is the number of the labial cuspules also a feature which was described in the diagnosis for truculentus and also in the key for the species of Euathlus and Phrixotrichus (see Perafán, C. & Pérez-Miles, F. (2014). Steffen Esche told me, that the males and females of the E. pulcherrimaklassi ( = Synonym of E. truculentus) and E. sp. BLUE, which he has examined, fits in this feature. Unfortunately, the editors of the Chilean site do not provide any information on this diagnostic feature.
That being said, the Exuviae we had for examination looked exactly the same color as what is pictured as Euathlus truculentus on the Chilean site.

 

[AphonopelmaTX]

I can understand your comment from the point of view of the purely morphological data on the mentioned page. However, the question arises whether the "forms" presented there, which seem to be almost identical to E. truculentus in terms of genital morphology, are in fact always different species, or - what I consider more likely - that they are merely local populations of Euathlus truculentus. It is remarkable that just the known different species like E. parvulus are morphologically easy and clear to separate from Euathlus truculentus. Beside the shape of the bulb and spermathecae is the number of the labial cuspules also a feature which was described in the diagnosis for truculentus and also in the key for the species of Euathlus and Phrixotrichus (see Perafán, C. & Pérez-Miles, F. (2014). Steffen Esche told me, that the males and females of the E. pulcherrimaklassi ( = Synonym of E. truculentus) and E. sp. BLUE, which he has examined, fits in this feature. Unfortunately, the editors of the Chilean site do not provide any information on this diagnostic feature.
That being said, the Exuviae we had for examination looked exactly the same color as what is pictured as Euathlus truculentus on the Chilean site.

It just so happens I have an adult female of what is referred to as Euathlus sp. Valparaíso (sold as Aphonopelma aberrans in 2016) which molted recently. This post got me off of my lazy butt to examine and image it for comparison to the Euathlus sp. Blue/ E. truculentus. You will notice that the number of labial cuspules in the attached photo equals 12 (less than 20 for E. truculentus), but the shape of the spermathecae is different from the illustrations in all descriptions of female E. truculentus. This is where I bring up the amount of variance allowed in the shape of the spermathecae for an identification of species "Valparaíso" as E. truculentus given the available literature describing the females.

I also have an immature female of the species sold as Euathlus sp. "Blue" that I am waiting on to grow up and provide an exuvium to examine and to compare with the "Valparaíso". These things take forever to grow up and I've been waiting for years already!

Given the images provided on this post of Euathlus sp. Valparaíso, would you identify it as E. truculentus?

I will tag Steffen on this post for his input as well. @c.h.esteban

 

[c.h.esteban]

Just a short note.
If i had learn something while my work with other genera (especially Pamphobeteus), so it is that, that sometimes morphological characters are useless without localities.
Thats why, have a look at these map. It´s my information about some similar Euathlus spp.
I hope it explains, my reasons to identify the sp. BLUE / sp. PICHIDANGUI / "pulcherrimaklaasi" as E. truculentus and why i be more careful with others like sp GREEN or sp VALPARAISO too.

 

[Theraphosid Research Team]

It just so happens I have an adult female of what is referred to as Euathlus sp. Valparaíso (sold as Aphonopelma aberrans in 2016) which molted recently. This post got me off of my lazy butt to examine and image it for comparison to the Euathlus sp. Blue/ E. truculentus. You will notice that the number of labial cuspules in the attached photo equals 12 (less than 20 for E. truculentus), but the shape of the spermathecae is different from the illustrations in all descriptions of female E. truculentus. This is where I bring up the amount of variance allowed in the shape of the spermathecae for an identification of species "Valparaíso" as E. truculentus given the available literature describing the females.

I also have an immature female of the species sold as Euathlus sp. "Blue" that I am waiting on to grow up and provide an exuvium to examine and to compare with the "Valparaíso". These things take forever to grow up and I've been waiting for years already!

Given the images provided on this post of Euathlus sp. Valparaíso, would you identify it as E. truculentus?

I will tag Steffen on this post for his input as well. @c.h.esteban

You already show clear differences of your Euathlus sp. "Valparaíso" compared to Euathlus truculentus. Not only the clearly different number of labial cuspules is remarkable, but also the structure of the spermathecae shows a clear difference, which in my eyes goes beyond the degree of intraspecific variation in E. truculentus. If one looks at the previously known spermathecae of Euathlus truculentus in the literature and compares them with the spermathecae of other Euathlus species, for example in the paper by Perafán & Pérez-Miles (2014), it is not difficult to see that the spermathecae within the species truculentus show only minor differences, but are clearly different from the other species. In my opinion, this circumstance is also present in the spermatheca shown by you, which is clearly structurally different from E. truculentus.

 

[AphonopelmaTX]

Just a short note.
If i had learn something while my work with other genera (especially Pamphobeteus), so it is that, that sometimes morphological characters are useless without localities.
Thats why, have a look at these map. It´s my information about some similar Euathlus spp.
I hope it explains, my reasons to identify the sp. BLUE / sp. PICHIDANGUI / "pulcherrimaklaasi" as E. truculentus and why i be more careful with others like sp GREEN or sp VALPARAISO too.

Thanks for showing the map. That definitely adds more support for the "blue femur" Euathlus sp. being E. truculentus.

You already show clear differences of your Euathlus sp. "Valparaíso" compared to Euathlus truculentus. Not only the clearly different number of labial cuspules is remarkable, but also the structure of the spermathecae shows a clear difference, which in my eyes goes beyond the degree of intraspecific variation in E. truculentus. If one looks at the previously known spermathecae of Euathlus truculentus in the literature and compares them with the spermathecae of other Euathlus species, for example in the paper by Perafán & Pérez-Miles (2014), it is not difficult to see that the spermathecae within the species truculentus show only minor differences, but are clearly different from the other species. In my opinion, this circumstance is also present in the spermatheca shown by you, which is clearly structurally different from E. truculentus.

Thanks for your input. I was also under the impression that the spermathecae of the "Valparaíso" was much too different from the illustrations in the literature to be E. truculentus, but a second opinion is always helpful.

Thanks again @c.h.esteban and @Theraphosid Research Team for your insightful and informative posts! There is always something new to learn from you two!