New and revised taxa of Neotropical Diplotaxini (Coleoptera: Melolonthidae): do they change the existing relationships? Revisiting systematics with morphological and molecular data
Author
Cherman, Mariana A.
Departamento de Zoologia, Universidade Federal do Paraná, Caixa Postal 19020, 81531 - 980, Curitiba, Paraná, Brazil & Departamento de Biologia e Zoologia, Instituto de Biociências, Universidade Federal de Mato Grosso, Av. Fernando Correia, no. 2367, Boa Esperança, 78060 - 900, Cuiabá, Mato Grosso, Brazil
marianabioar@gmail.com
Author
Basílio, Daniel S.
Departamento de Zoologia, Universidade Federal do Paraná, Caixa Postal 19020, 81531 - 980, Curitiba, Paraná, Brazil
Author
Clarkson, Bruno
Departamento de Zoologia, Universidade Federal do Paraná, Caixa Postal 19020, 81531 - 980, Curitiba, Paraná, Brazil & Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Av. Brasil, 4365, Pavilhão Mourisco, Manguinhos, 21040 - 360, Rio de Janeiro, Rio de Janeiro, Brazil & Laboratório de Entomologia e Fitopatologia, Universidade Estadual do Norte Fluminense Darcy Ribeiro, 28013 - 602 Campos dos Goytacazes, Rio de Janeiro, Brazil
Author
Agostinis, André O.
Departamento de Zoologia, Universidade Federal do Paraná, Caixa Postal 19020, 81531 - 980, Curitiba, Paraná, Brazil
Author
Smith, Andrew B. T.
Canadian Museum of Nature, 1740 Chemin Pink, Gatineau, Quebec, J 9 J 3 N 7, Canada
Author
Vaz-De-Mello, Fernando Z.
Departamento de Biologia e Zoologia, Instituto de Biociências, Universidade Federal de Mato Grosso, Av. Fernando Correia, no. 2367, Boa Esperança, 78060 - 900, Cuiabá, Mato Grosso, Brazil
Author
Almeida, Lúcia M.
Departamento de Zoologia, Universidade Federal do Paraná, Caixa Postal 19020, 81531 - 980, Curitiba, Paraná, Brazil
text
Zoological Journal of the Linnean Society
2024
2023-10-09
201
1
98
135
http://dx.doi.org/10.1093/zoolinnean/zlad115
journal article
10.1093/zoolinnean/zlad115
0024-4082
11241094
E6D9AF7E-F0AD-4656-B2F2-7FBFAA0312B3R
Genus
Homalochilus
Blanchard, 1851
(
FIG. 4A–H
)
Homalochilus
Blanchard 1851: 172
(original description);
Lacordaire 1855: 270
(redescription); Harold 1869: 1141 (catalogue);
Bruch 1911: 201
(catalogue); Dalla Torre 1913: 319 (catalogue);
Blackwelder 1944: 228
(catalogue);
Gutiérrez 1952: 211–212
, 213 (redescription, key);
Smith 1987: 62
(catalogue);
Evans 2003: 11
, 206 (systematics, catalogue);
Evans and Smith 2005: 170
(catalogue);
Evans and Smith 2009: 174
(catalogue);
Katovich 2008: 7
(systematics);
Krajčík 2012: 128
(catalogue);
Cherman
et al.
2016: 765
(systematics);
Cherman
et al.
2017:18
(systematics).
Type
species:
Homalochilus punctatostriatus
Blanchard, 1851
(here designated) [using Article 70.3.2 of the International Code on Zoological Nomenclature, 1999 to correct the misidentification of that species as
Homalochilus niger
by both
Gutiérrez (1952: 213)
and
Evans (2003: 11)
]. See details on
Homalochilus
monophyly, composition, and remarks in the systematics’ section (Discussion).
Taxonomic history of
Homalochilus
Blanchard (1851)
described
Homalochilus
based on two species:
H. niger
and
H. punctatostriatus
, both collected by M. d’Orbigny at the Patagonian Baie San-Blas (Bahia San Blas, southern
Buenos Aires
,
Argentina
). The author allied this genus mainly with
Diplotaxis
, with differences in the labium and the shorter body length. Some features mentioned by
Blanchard (1851)
present in both species of
Homalochilus
are: body coarsely punctate; clypeus broad, lamina-shaped; distal palpomere of maxilla oval; labium wide, enlarged laterally and truncate on apex, palpi inserted ventrally; prothorax wide; and elytra with apex rounded. The generic description (
Blanchard 1851
) stated other features found only in
H. punctatostriatus
: antennae with nine antennomeres; scutellum triangular; maxilla with two teeth on galea (
H. niger
has four); and the elytral apex rounded. This author also mentioned that the tarsi are cylindrical, not enlarged. This feature is controversial, as he used female
syntypes
(
Figs 5B, C
,
7B, F
) to describe each species, and enlarged tarsi is a dimorphic character in males of several species among Melolonthinae.
Figure 4.
Diagnostic features and transformations that support
Homalochilus
. Head in dorsal view (A), head and anterior portion of prothorax in dorsolateral view (B); head in frontal view (C); maxilla (D); labium (E); elytra, white square indicates erect setae (F); head, pronotum, scutellum and proleg (G), thoracic and abdominal ventrites, white lines indicate size of ventrites (H). White arrows in each figure indicate transformations and/or detailed features.
Lacordaire (1855)
allied
Homalochilus
almost entirely with
Liogenys
except that the maxillary palpi are shorter and wider, distal palpomere thick, oval, acuminate, and without fovea; head short, frons swollen and sloping on vertex; and in the clypeus rounded and weakly flanged. Different from what was stated by
Lacordaire (1855)
,
Homalochilus
species
do have fovea on the maxillar distal palpomere.
Lacordaire (1855)
mentioned proand mesotarsi weakly enlarged with pads in males, so we infer that he was referring to a series of
H. niger
with males and females.
Ohaus (1911)
described
Astaena bicolor
from a series of
seven specimens
collected in Córdoba (
Argentina
). Some of these specimens had been already identified as
A. discoidalis
Burmeister
by both Burmeister and Stempelmann, and others as ‘
A. bicolor
Burm.
’, the latter specimens belonged to W. Günther. Based on the identification label of these specimens bearing ‘
A. bicolor
’, Ohaus
described this species, and stated his doubt about the generic position due to the toothed mandible, which does not match with those of
Astaena
. According to
Ohaus (1911)
, the diagnostic features of
A. bicolor
are: body convex, black, weakly shiny, elytra red with margins black; clypeus large and trapezoidal, frons and vertex coarsely punctate and opaque; antenna with nine antennomeres; prothorax narrowed along its anterior margin; pronotal anterior corners projected; scales intercalated with bristles all along the pronotal margin; scutellum flat or depressed, smooth; elytra with sutural ridge bearing scattered, microscopic, yellow bristles, and apex bearing four-to-five brown, erect bristles; mesosternum reduced; propygidium very long, longer than pygidium, both equally punctate and covered with white, thick scales on the anterior margin, as well as the thorax and ventrites ventrally; tarsi cylindrical, slender; first tarsi with simple claws; mesotarsi and metatarsi with bifid claws.
Bruch (1911)
reported
H. niger
and
H. punctatostriatus
from ‘Patagonia’ and expanded the distribution of
Astaena bicolor
Ohaus
to
Tucumán
(
Argentina
).
The
Blackwelder (1944)
catalogue stated ‘Patagonia’ as the locality for both species of
Homalochilus
.
Gutiérrez (1952)
revised
Homalochilus
due to the ‘insufficient diagnoses of
Blanchard (1851)
’, and redescribed it based on the original descriptions and non-type specimens from Bruch’s collection housed at MACN.
Gutiérrez (1952)
suggested that the mandibles in
A. bicolor
are more alike to macrodactylines than those of sericines, as stated early by
Ohaus (1911)
.
Gutiérrez (1952)
synonymized
A. bicolor
with
H. punctatostriatus
and justified this nomenclatural act stating that specimens of
A. bicolor
are the males of
H. punctatostriatus
females, which was confirmed by Juan B. Bosq from the MACN. With this matching, Gutiérrez confirmed that, contrary to what was stated by
Lacordaire (1855)
, males of
H. punctatostriatus
do not have enlarged tarsi.
Gutiérrez (1952)
suggested that
Lacordaire (1855)
had been referring to males of a Catamarquian series of
Liogenys morio
Burmeister
instead of
H. punctatostriatus
(see
Liogenys niger
comb. nov.
further in this text).
Gutiérrez (1952)
presented a key to genera of ‘Liogenyina’ (
Homoliogenys
Gutiérrez
,
Manonychus
Moser
,
Homalochilus
,
Liogenys
, and
Pacuvia
) and redefined
Homalochilus
. In his diagnosis,
Gutiérrez (1952)
added new features and corrected others, as follows: frontoclypeal suture absent (considered present in the present work); inferior portion of eyes much larger than the upper; club as long as the funicle, shorter in females; short maxilla, galea bearing two teeth, distal palpomere fusiform (no mention about the fovea, which is present); pronotal anterior corners acute and projected, posterior corners rounded, scutellum 1.5 times longer than the width, apex acute; elytra short, enlarged on posterior third; subapical callus weakly marked; apical margin of each elytron rounded; fifth ventrite slightly longer than the others; propygidium very large and exposed, fused with tergite; mesotibia and metatibia with transverse carina complete, stronger in females; tarsi slender, cylindrical in both sexes; two metatibial spurs strongly uneven, the longest twice the length of the tibial diameter; claws bifid; in males the protarsal claws simple.
Gutiérrez (1952)
also expanded the geographic distribution of
Homalochilus
within
Argentina
, until then known only from
Buenos Aires
and ‘Patagonia’, to
Jujuy
,
Catamarca
,
Santiago del Estero
,
La Rioja
,
Mendoza
, and Cordoba provinces.
Gutiérrez (1952)
based the redescription of
H. niger
on a population from
Jujuy
composed of entirely black specimens similar to
H. punctatostriatus
(for more details see description of
H. nigripennis
). According to this author, the main features to distinguish
H. niger
(
sensu
Gutiérrez in this paragraph) from
H. punctatostriatus
are the size, the former being slightly larger; the elytra in colour, entirely black (
H. niger
) or red with margins black (
H. punctatostriatus
); and the ventral pubescence, bristled in thorax, lateral and disc of ventrites (
H. niger
) or scaly at these points, mainly on anterior margins of each ventrite (
H. punctatostriatus
).
Evans (2003)
designated
H. niger
as the
type
species of
Homalochilus
, which had been previously done by
Gutiérrez (1952)
, but neither of them examined the primary
types
.
Cherman
et al
. (2016)
tested the phylogenetic relationships among the Diplotaxini, and
Homalochilus
was recovered as monophyletic, supported by the following characters: elytral disc without pubescence (character 63); pygidial disc without bristles (character 129), and antennal club shorter than funicle. Though, in that analysis the characters were coded with the
syntypes
, which are females and are in poor conditions of conservation. Hence, the monophyly of
Homalochilus
obtained in that work is not reliable enough due to the number of missing states.
Etymology
From Ancient Greek ὁμαλός (
homalós
, ‘even, level’); χείλoς (
keilos
, ‘lip’) = labrum (Harold 1869); masculine in gender.
Diagnosis
Homalochilus
is distinguished from other Neotropical Diplotaxini by the following combination of characters: body short, sides parallel; black in colour, unicolorous or bicoloured (
Figs 5A
,
6A
); frons very wide, eyes barely seen dorsally, most surface ventrally (
Fig. 4A, B
); labrum with medial emargination deep in frontal view, (37:1) (
Fig. 4C
); maxilla curved (14:1), galea with two teeth (
Fig. 4D
); labium quadrangular, ligula and mentum fused (30:1), angles of ligula laterally projected behind the palp (29:0) (
Fig. 4E
); antennae uniformly black, with nine antennomeres (40:1), club as long as the funicle or shorter (128:1); pronotal anterior corners fused with hypomeron (
Fig. 4B
); mesocoxae slightly separated (81:0) (
Fig. 4H
); elytra flattened, short, leaving the propygidium exposed (
Fig. 5E
); long, four to five erect setae on each inner margin on apex of elytra (
Fig. 4F
); ventrite V longer than ventrite IV (105:0) (
Fig. 4H
); in males tarsomeres cylindrical (77:1) and ventral pads absent (78:1) in all legs (
Fig. 4G
); parameres with split beyond the midline (153:2).
Redescription
Length:
7.6–9.8 mm
; width: 4.0–
5.2 mm
. Body short, semiopaque, sides parallel, body, head, and pronotum black, elytra red on disc and black on margins (
H. punctatostriatus
) or entirely black (
H. nigripennis
).
Head
: frons almost as wide as the anterior margin of pronotum; eyes almost entirely placed laterally, ventral portion larger than dorsal portion (
Fig. 4A, B
); frons and clypeus coplanar; clypeus truncate (
H. punctatostriatus
) or rounded, subemarginate (
H. nigripennis
); galea of maxilla curved with two teeth, the apical the strongest (
Fig. 4D
); distal maxillary palpomere acuminate, fovea deep, almost sulcate, extending reaching the midline of the palpomere or extending past (
Fig. 4C
); labium widened at the transverse midline, slightly wider than it is long; sloped from the transverse carina towards apex (
Fig. 4E
); apical emargination wide and rounded; two labial palpomeres, the basal longer; antenna with nine antennomeres; black in colour; club as long as or shorter than the funicle.
Prothorax
: pronotal anterior corners scaly, fused with hypomeron; pronotal disc coarsely punctate, simple punctures sparsely disposed; posterior corners subangulate to sharp, obtuse angulate.
Pterothorax
: scutellum triangular, long; metacoxae equal in length or slightly shorter than the distance between mesocoxae and metacoxae.
Elytra
: flattened, glabrous, or with scattered bristles, length from 1.5 times up to two times that of the pronotum; four elytral ridges, the one or two outermost less noticeable; subapical callus strong, at the same level of the posterior inner corner of the sutural ridge; four to five erect setae on each inner margin on apex of elytra.
Legs
: three protibial teeth, the basal shorter than the other two, the apical obtuse in relation to longitudinal axis (
Fig. 4G
); mesotibia cylindrical, two transverse carinae, the apical complete in both sexes; all tarsi simple, protarsomere I slightly shorter than protarsomere II in both sexes.
Abdomen
: propygidium exposed, scaly in basal region, mostly glabrous; pygidium flat, as wide as it is long; subquadrate or subtrapezoidal; pygidial disc glabrous, scaly basally.
Dimorphism
Male:
metatibial spurs strongly uneven, the longest almost twice as long as the diameter of the tibial apex (
Figs 5F
,
6E
); protarsal claws simple (
Fig. 4G
), mesotarsal and metatarsal claws bifid, parameres with basal region strongly sulcate, basally widened and slightly inflated, parameres abruptly narrowed and dorsoventrally bent after the midline, width uniform towards the apex, apex curved downwards (
Figs 5G, H
,
6F, G
).
Female:
metatibial spurs uneven, the length of longer spur almost 1.5 the diameter of the tibial apex; all claws bifid.
Composition
Homalochilus punctatostriatus
and
Homalochilus nigripennis
.
Geographical distribution
ARGENTINA
(
Salta
,
Jujuy
,
Tucumán
? [according to
Gutiérrez (1952)
],
Catamarca
,
Santiago del Estero
,
La Rioja
,
Santiago del Estero
, Córdoba,
San Luis
,
Mendoza
, and
Buenos Aires
).
Remarks on
Homalochilus
phylogenetic relationships
Homalochilus
is the sister-clade of almost all Neotropical Diplotaxini, except for
Pacuvia
. It differs from (
Pachrodema
+ (
Careocallus
) +
Liogenys
)) in the frontoclypeal division complete (5:0), labium fused with ligula (30:1), apex never wider than the base (22:1); mentum without well-defined concavity on disc (32:1); and apex of metatibia not projected in males (142:1). At least nine of the diagnostic features of
Homalochilus
support the branch of the genus (
Figs 1–3
;
Table 1
). Characters that it has in common with other Neotropical Diplotaxini are: clypeus subemarginate (
Pachrodema
); frontoclypeal suture present, barely distinguishable (
Pachrodema
); nine antennomeres (a few
Liogenys
); base of sutural ridge of elytra along the entire scutellar margin (65:0) and first gap of elytral ridges less than two times the width of one ridge (66:1) (both latter characters shared only with
Careocallus
); mesotibia and metatibia with transverse carina complete in both sexes (some
Liogenys
and some
Pachrodema
); Character 84:1 (
Table 1
), was exclusive to
Liogenys
until the present analysis, and it is now shared with
Homalochilus
.
IDENTIFICATION KEY TO
HOMALOCHILUS
SPECIES
[MODIFIED FROM
GUTIÉRREZ (1952)
]
1. Anterior margin of clypeus widely truncate (
Fig. 5B
); elytra red on disc and black on outer margins, less than twice the length of pronotum (
Fig. 5A
); anterior margin of ventrites covered with scales (
Fig. 5D
) .............................................................. ........................................................................................................................................................................
Homalochilus punctatostriatus
-. Anterior margin of clypeus medially subemarginate (
Fig. 6B
); elytra entirely black, slightly more than twice the length of pronotum (
Fig. 6A
); anterior margin of ventrites glabrous or with bristles (
Fig. 6C
) ..........................
Homalochilus nigripennis