Heteragrion denisye sp. nov. (Odonata: Zygoptera: Heteragrionidae), a notable species from Serra da Canastra, Minas Gerais, Brazil
Author
Vilela, Diogo Silva
Author
Koroiva, Ricardo
Author
Guillermo-Ferreira, Rhainer
text
Zootaxa
2019
2019-09-19
4671
4
589
594
journal article
25448
10.11646/zootaxa.4671.4.10
762114a7-e97f-488a-816d-cc8c801c1ec4
1175-5326
3450444
CC043DC1-AD6B-4AA7-8888-5BE1E66D4D28
Heteragrion denisye
sp. nov.
(
Figs. 2a, c, d
;
3
and
4 a
̅e)
Holotype
.
³(
LESTES
,
RK054
),
BRAZIL
,
Minas Gerais
,
São Roque de Minas
,
Serra da Canastra National Park
(
-20.2323
,
-46.6085
,
1305 m
asl
),
25 x 2018
,
Diogo S. Vilela
,
Ricardo Koroiva
,
Vanessa Nobrega
&
Marcellus Lera
leg.
Etymology.
Named
denisye
(noun in genitive case) after Denisy Aparecida Silva, teacher, educator and beloved mother of the first author.
Description of
holotype
/
Head.
Labium light grey; labrum black; base of mandibles and genae black; remain- der of the head black, except for lighter spots lateral to each lateral ocellus and pale postocular lobes (
Fig. 2c
). Posterior head pale, with dark markings laterally.
Thorax.
Prothorax black dorsally; anterior lobe blue/grey laterally; middle lobe mostly blue laterally except for a small pale spot posteriorly; posterior lobe entirely black, bent caudad. Pterothorax black, with thin blue/pale stripes along the main thoracic sutures (mesopleural, metapleural and interpleural); remainder of thorax blue/grey. Legs; coxae pale grey, black medially; all femora and pro-, meso tibiae black externally, brown internally, metatibiae brown; spines longer than the space between them, becoming longer towards the apex on femora, and shorter towards the apex on tibiae; metatarsi missing (
Fig. 2a, d
).
Wings.
Hyaline, almost reaching S8; venation brown; pterostigma dark brown overlying 2 FW to 2 1/2 HW cells, oblique proximally; two postquadragular cells in FW and HW, 18 Px in FW, 16 HW (
Fig. 3
).
Abdomen.
Black, with pale basal rings from S3 to S7; S1 black dorsally, pale blue laterally; S2 with a pale area on its lower portion; ventroposterior portion of S8 and entire ventral portion of S9–S10 pale yellow.
FIGURE 2a, c–d.
Heteragrion denisye
sp. nov.
holotype from Serra da Canastra, Minas Gerais, Brazil. Head in dorsal view, pro and pterothorax in lateral view (a); head in dorsal view (c); pro- and pterothorax in dorsal view.
Figure 2b.
Heteragrion cyane
Machado & de Souza
, holotype from Barroso, Minas Gerais, Brazil. Head in dorsal view, pro and pterothorax in lateral view (b).
FIGURE 3.
Heteragrion denisye
sp. nov.
Holotype from Serra da Canastra, Minas Gerais, Brazil. Wings.
Anal appendages.
Black with dark brown coloration medially; ventrobasal expansion present, occupying at least 1/3 of the appendage; basal (BP) and medial portion (MP) subequal; medial portion dilated, almost rectangular, ventral branch of medial process plate-like with a bilobate apex and a distinct (almost straight) ridge; apical portion (AP) the shortest, ending with a beak-like blunt tip curved inwards (
Fig. 4
a–e). Paraprocts greatly reduced.
Measurements (in mm). FW: 24.5; HW: 23.4; Abdomen: 28.8; Total: 36.5.
Differential diagnosis.
Heteragrion denisye
belongs to Lencioni’s Group A, consisting of males lacking an elongated paraproct. It is a remarkable new species mainly due to its blue coloration pattern and cerci morphology. The cerci of
H. denisye
are easily distinguished from other congeners by the reduced apical portion, the latter elongated in most of Brazilian
Heteragrion
species, including those of Group A (see
Lencioni 2013
for a review of
Heteragrion
Group A). In
Heteragrion
, the apical portion of cerci is rarely shorter than the basal and medial portions. In Group A,
H. denisye
shares the short apical portion with
H. johndeaconi
and
H. gracile
.
Heteragrion denisye
can be easily distinguished from
H. johndeaconi
and
H. gracile
by exhibiting a blunt bilobated MP tip. The MP tip is rectangular shaped in
H. johndeaconi
and “W” shaped in
H. gracile
.
Two species that can be found in
Minas Gerais state
may resemble
H. denisye
:
H. cyane
and
H. obsoletum
Selys, 1886
.
Heteragrion denisye
occurs in a locality
400 km
away from the
type
locality of
H. cyane
(
Fig. 1
). Both species are only known from their
type
localities. In comparison with
H. cyane
(
Fig. 4
),
H. denisye
exhibits the three portions of the cerci with some differences. In
H. denisye
, BP and MP are subequal in size and AP is visibly the shortest portion. In
H. cyane
, BP is the shortest whereas MP and AP are subequal. Both
H. denisye
and
H. cyane
have a ventrobasal expansion on the basal portion of cerci, less concave in
H. cyane
(
Fig. 3a
) in comparison to
H. denisye
(
Fig. 4c
).
Heteragrion denisye
has a ventral branch on MP, with a rectangular plate-like conformity (MP in
Fig. 3a
), similar to
H. cyane
(MP in
Fig. 4c
). However, in the latter, the apex of MP is rounded, while
H. denisye
has MP with bilobated apex.
As for
H. obsoletum
, the only comparable trait Selys (1886) mentions for
H. obsoletum
is that “un renflement ou dent interne arrondie après leur milieu”, suggesting that male cerci have rounded MP. Therefore, here we consider that
H. denisye
may be distinguished from
H. obsoletum
by the presence of a bilobed MP, rounded in
H. cyane
. We cannot make further accurate comparisons or associate
H. obosoletum
with any known
Heteragrion
species because of the problematics involved. First, the validity of
H. obsoletum
is yet to be addressed until the
holotype
is found or a
neotype
designated. The only known specimen had its cerci lost before Selys finished its description (Selys 1886, p. 58) and nothing is known of the whereabouts of the
holotype
, except for its original label in the RBINS collection (Jérôme Constant pers. comm.;
Fig. 5
).
Machado & Souza (2014)
mentioned that the description of
H. obsoletum
made by Selys (1886) is very poor in terms of structural characters, what hampers comparisons. Moreover, in a personal communication, Marcel Wasscher mentioned that “Unfortunately, Selys had made no drawing or notes on that species”. Second, the type locality of
H. obsoletum
, Caxambu
, has been visited by Ângelo Machado in several expeditions, nevertheless, specimens of
H. obsoletum
could never be found (Ângelo Machado pers. comm.). Moreover, Caxambu is distant from the type localities of
H. cyane
and
H. denisye
(
Fig. 1
).
FIGURE 4a–e.
Heteragrion denisye
sp. nov.
Holotype from Serra da Canastra, Minas Gerais, Brazil. Cerci morphology (a); cerci in: dorsal view (b); mediolateral view (c); mediodorsal view (d); ventral view (e).
Figure 4f–h.
Heteragrion cyane
Machado & de Souza
, holotype from Barroso, Minas Gerais, Brazil. Cerci in: mediodorsal view (f); dorsal view (g); lateral view (h). BP: basal portion; MP: medial portion; AP: apical portion.
Habitat and Ecology.
This species was collected in a first order stream near to a Vereda (i.e., palm swamp) within the altitude fields (which differs from the surrounding phytophysiognomies mainly by its sparse vegetation, lacking woods and often occurring>
1.300 m
asl) of the park (
27 km
from São Roque de Minas, entrance to the Serra da Canastra National Park,
Fig. 6
). The species was found perching on a shaded area of the stream (
Fig. 6a
), which was quite difficult to access due to the tall grass and muddy soil. We collected several
Peristicta
spp., a couple
Argia
sp. and one female
Franciscagrion franciscoi
Machado & Bedê,
2016 in
the same area.
Final remarks
. Most
Heteragrion
species are often characterized by their yellow/orange body coloration contrasting with dark pterothoracic stripes, mainly on the middorsal carina and mesepimeron. However, coloration seems to be a plastic trait even among conspecifics, therefore, should not be considered a reliable character for taxonomic use (
Lencioni 2013
). Nevertheless, some species are known to exhibit colors that diverge from the common yellow/orange/black pattern, which are easily recognizable both in the field and in collections. For example,
Machado & de Souza (2014)
described
H. cyane
from Minas Gerais state, a remarkable species with a blue/black body pattern.
Dunkle (1989)
described
H. azulum
from a single male collected in
Mexico
, with blue-gray bands on the pterothorax and orange coloration from segments eight to ten.
Heteragrion inca
Calvert, 1909
also seems to present some blue thoracical colors (Rosser Garrison pers. comm).
Heteragrion denisye
is certainly a remarkable species in terms of coloration, being easily distinguished from other
Heteragrion
.
Finally,
H. denisye
was found within a National Park that harbors many endemic and poorly known species (
Machado & Bedê 2015
;
Novaes
et al.
2018
;
Cezário
et al.
2018
, in press). Furthermore, the habitat in which
H. denisye
was collected differs from the areas where it is common to find other
Heteragrion
species (
Fig. 6
). Instead of inhabiting shaded areas in dense forests,
H. denisye
was found in a small patch of vegetation in an open field (
Fig. 6a
̅b). The discovery of this new species justifies the actions for species conservation in the National Park, such as the expeditions that resulted in this study, which are essential for monitoring populations of these rare and already endangered species. Furthermore, the altitude fields are known for their high degree of fauna endemism, yet are one of the most susceptible to anthropic pressures (
Vasconcelos 2014
). Therefore, more collections are needed in the immediate surroundings and other areas of the park to find additional populations of these species.