A revision of Macromalthinus Pic, 1919 with description of six new species (Coleoptera: Cantharidae: Chauliognathinae)
Author
Biffi, Gabriel
Author
Constantin, Robert
text
Papéis Avulsos de Zoologia
2018
Pap. Avulsos Zool., S. Paulo
2018-11-29
58
1
22
http://dx.doi.org/10.11606/1807-0205/2018.58.58
journal article
10.11606/1807-0205/2018.58.58
1807-0205
5384147
97C262C2-6F02-4916-9533-43653FE5561F
Macromalthinus schmidli
Constantin, 2010
(
Fig. 54
)
Macromalthinus schmidli
Constantin, 2010a: 24
.
Material examined:
HOLOTYPE
♂
:
ECUADOR
.
Zamora
, EstaciónCientíficaSanFrancisco,
LomaMoras
,
03°58’30”S
,
79°04’38”W
,
2,000 m
,
X.2008
,
J. Schmidl
(
NHMB
) (
Fig. 54
).
Differential diagnosis:
Head, pronotum and elytra entirely black; males: fore femur strongly swollen with a small, sharp, apical ventral tooth; aedeagus with right prolongation of tegmen broad; left setiferous prolongation short; females: ventrite VII wide, lateral margins broadly arched, posterior margin slightly projected.
Macromalthinus schmidli
differs from all the other species by head, pronotum and elytra entirely black, and fore femur of males strongly swollen, with a small apical ventral tooth.
Distribution:
Ecuador
(
Fig. 66
).
Remarks on morphology
One of the diagnostic characters ascribed for
Macromalthinus
is the abdomen of males curved under itself in rest position (
Brancucci, 1981a
) (
Fig. 59
). Actually, this curvature is the consequence of dehydration of the broad membranes between abdominal ventrites (
Fig.60
) and depends on the killing and preserving methods applied to the specimens. When alive, the abdomens of males are normally straight (
Fig. 61
).
Female genitalia of
Macromalthinus
species
(
Fig. 62
) have characters in common with both members of Chauliognathini and Ichthyurini genera, according to the general morphological configuration outlined by
Brancucci (1980)
. In all studied species, the vagina is sacciform, abruptly constricted before bursa copulatrix; oviduct joining vagina ventrally; accessory gland dorsally; bursa copulatrix globose, very small; spermatheca consisting of a tuft of spiralling filaments joining the bursa copulatrix anteriorly by a short duct.
According to
Brancucci (1980)
, the wings of Chauliognathinae are somewhat constant, with minor differences distinguishing the two tribes,Chauliognathini and Ichthyurini.
Macromalthinus
species
show the same general aspect of that described by
Brancucci (1980)
as ‘
type
Chauliognathus
’: wing veins reduced; veins r and r-m present; radial cell 2R₁ closed; vein Rr extending just until meeting point with r-m; vein Mr sclerotized; transversal vein cu-a absent; margin of anal area slightly sinuous. However, some of the differences observed in
Macromalthinus
species
from that basic model resemble the Ichthyurini wings highlighted by
Brancucci (1980)
: wings much longer and narrower; base much narrower than distal half; vein Cu straight, without distinct limits from M₃
₊
₄; vein Ax2 fading, not visible throughout its length; vein Mr running very close to M₃
₊
₄ (
Fig. 58
).
Morphologically, two main groups of species can be recognized in
Macromalthinus
.
In the first, composed of
M. maximiceps
,
M. belemensis
,
M. santaremensis
,
M. globuliventris
,
M. schmidli
,
M. guyanensis
sp. nov.
,
M. orapuensis
sp. nov.
,
M. piceiventris
sp. nov.
and
M. luteoapicalis
sp.nov.
, the specimens are larger,more robust and with a strong constriction near the anterior angles of pronotum (
Figs. 7-10
), and aedeagus with a large and broad right prolongation of tegmen (
Figs. 31-34
). The second group is composed of
M. brasiliensis
,
M. xerophilus
sp. nov.
and
M. quadratithorax
sp.nov.
Specimens of these species are smaller,with a subquadrate pronotum (
Figs. 11-12
), without strong constrictions near anterior angle; right prolongation of tegmen shorter and narrower (
Figs. 35-36
).
The setiferous prolongation can be very long (
M.maximiceps
,
M. belemensis
,
M. santaremensis
,
M. luteoapicalis
sp.nov.
)(
e.g.,
Fig.32
) to short and broad (
M.globuliventris
,
M. schmidli
,
M.piceiventris
sp. nov.
,
M. guyanensis
sp. nov.
,
M. orapuensis
sp. nov.
,
M. quadratithorax
sp. nov.
) (
e.g.,
Figs. 31, 33-35
), or totally absent (
M. xerophilus
sp. nov.
,
M. brasiliensis
) (
Figs. 36
,
65
). According to
Brancucci (1981a)
, the genus encompasses typical, morphologically resembling species, except for
M. brasiliensis
,
which seemed to be the transition between
Macromalthinus
and
Maronius
.
Macromalthinus xerophilus
sp. nov.
and
M. quadratithorax
sp. nov.
resemble
M. brasiliensis
in the pronotum with feebly constricted lateral margins, and tegmen with narrower right prolongation and absence of setiferous prolongation.
Figures 59-65: Morphology of
Macromalthinus brasiliensis
.
(59) Habitus of male, lateral view. (60) Abdomen of male, ventral view. (61) Live specimen, male. (62) Genital organs of female,lateral view.(63-65) Aedeagus,left,dorsal and right view.Abbreviations:ag = accessory gland,bc = bursa copulatrix,ov = oviduct, sp = spermatheca,v = vagina.
Distribution and natural history of
Macromalthinus
Distributional data known prior to this work showed restricted distribution records and wide disjunction of species (
Brancucci, 1981a
;
Constantin, 2010a
, 2016). The species of this genus were recorded only from
French Guiana
(
M. maximiceps
),
Ecuador
(
M. schmidli
),
Peru
(
M. globuliventris
), northern (
M. belemensis
,
M. santaremensis
) and southeastern
Brazil
(
M. brasiliensis
). New records fill wide distributional gaps of
Macromalthinus
species
in South America and approximate formerly widely separated species (
Figs. 66-69
).
Figures 66-69: Distribution of
Macromalthinus
species.
(66) Distribution of
Macromalthinus
species
in South America. (67) Distribution of
M. brasiliensis
in Brazil.(68)Distribution of
M.maximiceps
in French Guiana.(69)Distribution of
M.guyanensis
sp.nov.
,and
M.orapuensis
sp.nov.
in French Guiana.Background maps of Figs.66-67 by Natural Earth (available at:www.naturalearthdata.com), and Figs.68-69 by Eric Gaba.
Some species are still known only from single or nearby localities, like
M. globuliventris
,
M. schmidli
and
M. santaremensis
,
whereas for others the known distribution is broadly expanded, like for
M. maximiceps
,
M. belemensis
and
M. brasiliensis
.
Members of the genus are record- ed for the first time in
Trinidad and Tobago
(
Trinidad Island
) and in northeastern, middle-western and southern
Brazil
, embracing a wide range of biomes, vegetation
types
, climates and altitudinal ranges. Most of the species inhabit very humid, sometimes flooded regions and gallery forests in central Amazon (like
M. belemensis
,
M. santaremensis
and
M. piceiventris
sp. nov.
) or along the northern and southern reaches of Amazon (like
M. maximiceps
,
M. orapuensis
sp. nov.
,
M. guyanensis
sp. nov.
and
M. luteoapicalis
sp. nov.
).
Macromalthinus brasiliensis
is widespread in several vegetation
types
along the southern and southeastern Brazilian Atlantic forest, like the coastal tropical moist broadleaf
restinga
forest at the seashore,
campos rupestres
highlands (shrubby montane savannas), montane forests, dryer inland areas and in small forest patches in metropolitan areas (
São Paulo
city). In contrast,
M. xerophilus
sp. nov.
is only recorded from a transition zone between the Atlantic forest and the semiarid
caatinga.
The specimens are usually collect- ed with malaise traps or by sweeping the lower shrubby vegetation.
Nothing is known about feeding habits of
Macromalthinus
.
It seems that there are not specific food sources,as seen by the wide distribution of some species throughout such distinct vegetation
types
, biomes and altitudinal ranges.