the cynipoid genus paramblynotus - American Museum of Natural ...

2007 LIU ET AL.: REVISION OF PARAMBLYNOTUS (HYMENOPTERA) 5
distinctly defined, its ventral margin is not
evenly curved (Ronquist, 1995b). Thus, despite
the secondary loss in the yangambicolus
group, the ventrally defined mesopleural
triangle remains a viable synapomorphy for
Paramblynotus species.
The second Paramblynotus synapomorphy,
the dorsally enlarged sixth abdominal
tergum, is a unique feature for Paramblynotus
among all cynipoids. In the Oberthuerellinae,
the sixth abdominal tergum is also the
largest metasomal tergum, but in this subfamily
the tergum is expanded ventrally as
well as dorsally, giving it a completely
different shape that has apparently been
independently derived. Within Paramblynotus,
there are two obvious subsequent modifications
of the sixth tergum. In P. mixtus
of the yangambicolus group, tergum 6 has
become subequal to the three proceeding
terga dorsally, although it is still distinctly
expanded dorsally compared to its width
laterally. In the African trisetosus group,
tergum 6 is expanded dorsally, but this is
difficult to see because it is partially covered
by the more strongly expanded tergum 5.
A third potential synapomorphy of Paramblynotus
discussed by Ronquist (1995a) is
the internalization of abdominal sterna 4–6,
a feature present in all species except the
clade of P. yangambicolus and P. alveolatus.
According to the phylogenetic analysis presented
here, the exposed sterna in the latter
clade are most probably due to secondary
reversal. However, the interpretation of this
character is still complicated because all other
members of Liopteridae, except species of
Kiefferiella, share the Paramblynotus state of
having sterna 4–6 entirely covered by sternum
3. Thus, it is possible that internalization
happened twice, once in the ancestor of
Paramblynotus and once in the ancestor of all
liopterids except the Mayrellinae, making this
character a Paramblynotus synapomorphy.
However, an equally parsimonious explanation,
given that forward and backward
changes carry the same cost, is that the
internalization is a ground-plan feature of
liopterids and that the sterna became secondarily
exposed in Kiefferiella and in some
Paramblynotus. Dissection of a few liopterids
with concealed sterna (species of Pseudibalia
and Paramblynotus) revealed that the sterna
are still independent, free, and well-pigmented
sclerites even though they are covered by
abdominal sternum 3 in normal repose. The
presence of free sclerites presumably facilitates
repeated reversal to the primitive
condition.
The genus Paramblynotus was originally
placed in the Figitinae (Cameron, 1908) but
was later moved to the Liopterinae (Weld,
1930). Hedicke and Kerrich (1940) promoted
the subfamily Liopterinae to family status
and, in the same paper, Kerrich established
a new subfamily Mesocynipinae including
five genera, namely Mesocynips Cameron,
1903, Paramblynotus Cameron, 1908, Dallatorrella
Kieffer, 1911, Mayrella Hedicke,
1922, and Paribalia Weld, 1922. Before that,
Kieffer (1911) had established a subfamily
Dallatorellinae for his new genus Dallatorrella,
and Hedicke (1922) had proposed
another subfamily, Mayrellinae, to include
his genus Mayrella. In abandoning the two
existing subfamily names, Hedicke and Kerrich
(1940) apparently recognized Cameron
(1903) as the author of Mesocynipinae.
However, Cameron had only mentioned in
the description of Mesocynips that it deserved
to be placed in a separate subfamily; the
complete lack of a description of the new
subfamily or even mention of its name makes
it impossible to attribute the subfamily to
him.
The arrangement of Hedicke and Kerrich
essentially remained unchanged until the
recent phylogenetic studies of Ronquist
(1995a, 1995b). According to Ronquist
(1995a, 1995b), the Liopteridae is monophyletic,
constituting the sister group of all
other cynipoids excluding Austrocynipidae
and Ibaliidae (fig. 3). Ronquist (1995a) divided
the liopterids into four monophyletic
subfamilies: Liopterinae, Oberthuerellinae,
Dallatorrellinae, and Mayrellinae. Of the
Mesocynipinae genera of Hedicke and Kerrich
(1940), Mesocynips and Dallatorrella
were placed in Mesocynipinae and the others
were all grouped into the more widely
circumscribed genus Paramblynotus and
placed in the Mayrellinae together with
Kiefferiella and Decellea. Ronquist also
showed that the Mayrellinae are the sister
group of all the remaining liopterids and
suggested that Kiefferiella forms the sister