The earliest beetle with mouthparts specialized for feeding on nectar is a parasitoid of mid-Cretaceous Hymenoptera
Author
Batelka, Jan
Department of Zoology, Faculty of Science, Charles University, ViniČná 7, 128 00 Praha 2, Czech Republic
janbat@centrum.cz
Author
Prokop, Jakub
Department of Zoology, Faculty of Science, Charles University, ViniČná 7, 128 00 Praha 2, Czech Republic
text
BMC Ecology and Evolution
2021
207
2021-11-22
21
1
1
12
http://dx.doi.org/10.1186/s12862-021-01930-6
journal article
10.1186/s12862-021-01930-6
b2e4e166-7297-45a5-82eb-84937eb7233a
PMC8607574
34809578
5733385
Description of
Salignacicola
ebboi
(Perrichot, Nel et Néraudeau, 2004)
,
a species originally placed within
Macrosiagonini
, cannot be compared with other ripiphorids because of absence of some important information. Several of the most prominent characters of this fossil can be, however, preliminarily reconsidered in the context of certain ripiphorid lineages or genera as follows:
1) Tibial spur formula 1-2-2. Reduction in the number of tibial spurs is common in various lineages of
Ripiphoridae
(see above comments for character 2 under
Melanosiagon
gen. nov.
) and occurs also in most
Macrosiagonini
.
2) Antennomeres III–XI (X) in males with single long projection. Character present in all
Ptilophorinae
,
Pelecotominae
and
Hemirhipidiinae
, and most
Ripidiinae
(except for several genera with filiform antennomeres and
Paleoripiphorus
with biflabellate antennae). In males of
Ripiphorinae
antennomeres III–X (IX) always have two long rami.
3) Tread-like antennal rami. Present in some species of
Macrosiagon
(see above comments for character 3 under
Melanosiagon
gen. nov.
).
4) Long hair-like sensilla on antennal rami. Similar sensilla occur in several species of
Ptilophorus
Dejean, 1834
inhabiting Socotra, Central Asia and USA [
37
]. Homology of this character in
Salignacicola
gen. nov.
and the modern offshoot
Ptilophorus
,
is unlikely.
5) Reduced wing venation. Tis character state is present in all
Ripidiinae
[
38
] and
Ripiphorinae
, but in both subfamilies the venation is quite different [
26
,
27
].
6) Abdomen is 9-segmented.
Ripiphoridae
(except for
Ripidiinae
) have a 5-segmented abdomen. Up to seven visible segments are discernible in some fossil
Ripidiinae
with
VIIIth
and
IXth
segment visible as internal structures [
38
]. In
Salignacicola
gen. nov.
the reported number may be incorrect: five translucent telescopically overlapping segments would appear to be nine units. Tis character should be reinvestigated.
7) Legs long and slender with apical setal fringes on tibia and tarsomeres. Typical for
Macrosiagonini
(like
Metoecus
),
Pelecotominae
and
Hemirhipidiinae
. In
Ptilophorinae
they are much shorter and stronger, in
Ripidiinae
distinct tibial and tarsal setal fringes are absent.
8) Long meta(tibial) spurs. Present only in
Ptilophorinae
and
Ripiphorinae
(see above comments for character 9 under
Melanosiagon
gen. nov.
).
9) Serrate pretarsal claws. Now known in both
Ripiphorinae
tribes,
Ptilophorinae
, and South American
Pelecotominae
(see above comments for character 10 under
Melanosiagon
gen. nov.
).
Salignacicola
gen. nov.
shares characters 1, 3, 5, 8 and 9 with
Ripiphorinae
as the subfamily is now understood (i.e., including
Melanosiagon
gen. nov.
), but uniflabellate antennae (character 2) excludes
Salignacicola
gen. nov.
from
Ripiphorinae
more basally or it might require (depending on the shape of the sclerites on the metathorax) redefinition of this character in this subfamily. Long hair-like sensilla on antennal rami (character 4) can be interpreted as an apomorphy of the genus, but not as synapomorphy with certain recent species of
Ptilophorus
bearing similar sensilla.
Salignacicola
gen. nov.
thus, may represent a stem lineage of
Ripiphorinae
(retaining the uniflabellate antennae of its ancestors), which went extinct at the end of Cretaceous, but its exact phylogenetic position within the subfamily will remain unclear until the critical characters of the holotype are reinvestigated using micro-CT and redescribed in accordance with the high standard of the descriptions of most of the
Ripiphoridae
entrapped in very transparent Burmese amber.