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Journal archives for September 2021

September 09, 2021

Erotylus. Histrio group

This post is a summary of the differences the species of Erotylus from histrio group present.

Introduction

Erotylus is a genus of Erotylidae pleasing fungus beetles with around 100 described species. In 1907-08 Paul Kuhnt divided them in groups according to some characteristics. This post is about the first group, The histrio-group, which his words are "Large species with squat-like, blunt elevation somewhat behind the middle of the elytra; Elytra more or less pointed towards the back. Usually a red spot on the shoulder and a point on the tip, as well as a round yellow spot next to the scutellum (often connected to each other)."

There are 8 species in this group:

Erotylus histrio, E. mirabilis, E. elegans, E. histrionicus, E. chevrolati, E. aegrotus, E. clarosignatus and E. permutatus

Kuhnt created a key with the main differences to which I adapt and illustrate below:

A. Area around the scutellum remains black; 6 yellow bands running from the edge up to the hump

…………………………. E. mirabilis.


B. One yellow spot next to the scutellum (sometimes combined with the yellow bands/spots behind)

Posted on September 09, 2021 01:33 by fmiudo fmiudo | 1 comment | Leave a comment

September 30, 2021

Erotylus incomparabilis fixing needed.

By the time I'm writing this post, there is about 50 observations of pleasing fungus beetles of the genus Erotylus identified as Erotylus incomparabilis (Perty, 1832) here on iNaturalist. In my opinion they are incorrectly identified and we should try to fix that. Several other places in the internet are also incorrect.

I'm making this post so that I can use it as reference for when I'm fixing the IDs on those observations in the following days, but first let me explain what E. incomparabilis is.

The species was firstly described in 1832 in the work Delectus animalium articulatorum : quae in itinere per Brasiliam by the illustrator and contributor Maximilian Perty. His diagnosis in short Latin was:

"ovalis, gibbus, niger, elytris coccineis, ad basin, nigris, flavopunctatis, postice nigro undidatis. - Long. 8 mm. - Amazon River.

Which we can translate to "Oval, convex, black, elytra red but black at the base, with yellow punctures and with black waves at the apical part."

Later Lacordaire didn't bring more details, but both Perty and Lacordaire brought drawings for the species.

Perty's drawing of E. incomparabilis (Figure 8)

Lacordaire's drawing of E. incomparabilis (Figure 4)

Crotch was the first to tell us that this was the most variable species of the genus. Kuhnt exemplified some other variants. Kuhnt also made a deep study about this genus and divided the species in several groups. Erotylus incomparabilis was put inside the group #5; The Varians Group, which characteristic is "by combining narrow bands, wide bands are created; at most 3 bands are available." This group had 14 species (counting E. incomparabilis) at the time.

A recent work about another genus Erotylina brought a very interesting image of a beetle drawer that gathered several, if not all, of the variations.

A collection of pinned specimens of Erotylus showing several instances of E. incomparabilis.

So based on these evidences and descriptions we are better raising the ID of those observations to the genus level Erotylus at least, since, unfortunately this genus has several species with very subtle differences between them, so we might not be able to replace a species for another in this case. The last through study on those beetles is 100+ years old... Hopefully new studies such as the recent one about Erotylina leoparda can shed some light on Erotylus too, and we might find several synonyms.

Perty plate https://www.biodiversitylibrary.org/page/47586660
Perty original description https://www.biodiversitylibrary.org/page/4758a6503
Lacordaire plate https://www.biodiversitylibrary.org/page/42570161
Lacordaire description https://www.biodiversitylibrary.org/page/11545287
Crotch description https://www.biodiversitylibrary.org/page/9797149
Kuhnt description https://www.biodiversitylibrary.org/page/33769526
Erotylina study (source of beetle drawer image) https://doi.org/10.1590/0001-3765202120201452

Posted on September 30, 2021 23:39 by fmiudo fmiudo | 0 comments | Leave a comment

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