A hypothetical evolutionary history of passalid beetles narrated by the comparative anatomy of the hindgut (Coleoptera: Passalidae)
Author
Fonseca, Claudio Ruy Vasconcelos Da
Author
Barbosa, Márcio Luís Leitão
Author
Fernandez, Maria Fernanda Souza
text
Zootaxa
2011
3012
1
20
journal article
46432
10.5281/zenodo.200834
0d504835-4a24-4134-ae33-9448d9fb5884
1175-5326
200834
Subfamily
Aulacocyclinae
Kaup, 1868
(
Fig. 1
)
The genera
Aulacocyclus
Kaup
(
Fig. 1
A),
Comacupes
Kaup
(
Fig. 1
B),
Taeniocerus
Kaup
(
Fig. 1
C),
Cylindrocaulus
Fairmaire
(
Fig. 1
D) and
Ceracupes
Kaup
(
Fig. 1
E) are included in this subfamily. The ileum in these genera is similar to
Scarabaeidae
(
Umeya 1960
;
López-Guerrero 2002
), where the diverticula are assembled around the proximal edge and vary in shape and number. There are about six diverticula in
Comacupes
and none in
Cylindrocaulus
, but the average is three to four for the subfamily.
As
to segmentation, there is variation from broad (
Comacupes
) to close clustering, which makes the ileum look bellow-shaped (
Cylindrocaulus
).
FIGURE 1.
Aulacocyclinae
hindgut. A—
Aulacocyclus edentulus
(MacLeay)
, Australia; B—
Comacupes cylindraceus
(Perty)
, Philippines; C—
Taeniocerus bicanthatus
(Percheron)
, Borneo; D—
Cylindrocaulus bucerus
Fairmaire
, Japan; E—
Ceracupes fronticornis
(Westwood)
, Taiwan.
Branch Solenocyclinae+
Figs 2–8
This branch embodies all genera that are part of
Passalinae
in Reyes-Castillo’s (1970) classification. The features of the ileum confirm this observation, as it is obvious that Solenocyclinae+ is the sister group of
Aulacocyclinae
. Concerning the ileum architecture, Solenocyclinae+ show transformations that start to become noticeable on the African genera
Stephanocephalus
Kaup
(
Fig. 2
C),
Didimus
Kaup
(
Fig. 2
D),
Pentalobus
Kaup
(
Fig. 2
E),
Semicyclus
Kaup
(
Fig. 2
F) and
Flaminius
Kuwert
(
Fig. 3
E), possessing a collection of protuberances in the distal half. In
Solenocyclus
Kaup
(
Fig. 3
A),
Vitellinus
Kuwert
(
Fig. 3
B),
Ciceronius
Kaup
(
Fig. 3
C) and
Erionomus
Kaup
(
Fig. 3
D), such protuberances extend their range to cover the whole surface of the ileum. The number and size of the protuberances are not constant, as sometimes they can be dense in
Leptaulax
Kaup
(
Fig. 2
B), giving a very striking differentiation to the ileum. In addition to the protuberances, the long diverticula, which arise from the proximal region in
Aulacocyclinae
, undergo shortening in the Solenocyclinae+, and in some instances turning into just one diverticulum. Protuberance clustering increases in taxa from Indo-Australian
Pleurarius
Kaup
(
Fig. 7
A) to Neotro- The Neotropical
taxa
are included in two tribes: Passalini and
Proculini (
Boucher 2006
)
. The ileum in most genera of
Proculini
(exposed clypeus);
Odontotaenius
Kuwert
(
Fig. 4
A),
Spurius
Kaup
(
Fig. 4
B),
Popilius
Kaup
(
Fig. 4
C),
Pseudacanthus
Kaup
(
Fig. 4
D),
Vindex
Kaup
(
Fig. 4
E),
Petrejoides
Kuwert
(
Fig. 4
F),
Heliscus
Zang
(
Fig. 4
G),
Chondrocephalus
Kuwert
(
Fig. 4
H),
Verres
Kaup
(
Fig. 5
A),
Veturius
Kaup
(
Fig. 5
B) and
Proculejus
Kaup
(
Fig. 5
C); has the long diverticulum facing down. The long diverticulum faces up for
Proculus
Kaup
(
Fig. 5
G), in which the ileum is formed by large diverticula on the proximal region that becomes smaller towards the distal apex. On the other hand, the large, closely clustered protuberances distinguish
Proculus
from all other
Proculini
. In the Passalini (hidden clypeus);
Ptichopus
Kaup
(
Fig. 6
A),
Passalus
(
Fig. 6
B),
Spasalus
Kaup
(
Fig. 6
C),
Paxillus
MacLeay
(
Fig. 6
D) and
Passipassalus
Fonseca & Reyes-Castillo
(
Fig. 6
E); the ileum becomes flattened and the protuberances increase from four to six rows, becoming noticeably denser in Macrolininae.