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

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4 BULLETIN AMERICAN MUSEUM OF NATURAL HISTORY NO. 304 America and consists of one fossil species and four extant species, two of which are described (Ronquist, 1995a). The current knowledge of the biology of the Mayrellinae is based on a few rearing and collecting records. These suggest that the Paramblynotus species are parasitoids of wood-boring Coleoptera of the families Cerambycidae (Diaz, 1973; Yang and Gu, 1994; Ronquist, 1995a) and Curculionidae, and possibly also Hymenoptera of the family Siricidae (Yang and Gu, 1994). Decellea has been reared from Coleoptera as well as from Lepidoptera (Ronquist, 1995a), and species of Kiefferiella are parasitoids of Buprestidae (Coleoptera) (Weld, 1956). In all cases, mayrellines have been associated with broadleaved trees and bushes (Weld, 1956; Ronquist, 1995a), never conifers; the plant records include members of the families Asteraceae, Chenopodiaceae, Euphorbiaceae, Fabaceae, Fagaceae, Lauraceae, Myrtaceae, Oleaceae, Pteroxylaceae, and Ulmaceae (Ronquist, 1995a and references therein; this study; Schick, personal commun.). The circumscription of the genus Paramblynotus has changed considerably since its establishment by Cameron (1908). Several genera have been synonymized with Paramblynotus, including Paraegilips Kieffer, 1910 (Hedicke and Kerrich, 1940; Weld, 1952; Ronquist, 1995a), Allocynips Kieffer, 1914 (Weld, 1930), Holocynips Kieffer, 1916 (5 Diholocynips Rohwer and Fagan, 1917) (Ronquist, 1995a), Mayrella Hedicke, 1922 (Weld, 1952), Paribalia Weld, 1922 (Ronquist, 1995a), Stylobrachys Belizin, 1951 (Kovalev, 1994), Baviana Barbotin, 1954 (Weld, 1962), and Decellea Benoit, 1956 (Weld, 1962; but see Ronquist, 1995a). The concept of the genus adopted in this study is based on Ronquist (1995a) except for a few changes motivated by the results of the phylogenetic analysis. The genus Paramblynotus is considered a monophyletic group supported by two derived features (Ronquist, 1995a): (1) ventral margin of mesopleural triangle well defined and evenly curved (fig. 1), and (2) abdominal tergum 6 of females distinctly expanded dorsally to form the largest metasomal tergum (fig. 2). The first character is shared by all Paramblynotus species except Figs. 1, 2. Apomorphies for Paramblynotus. 1, Ventral margin of mesopleural triangle is smoothly curved and well defined (P. virginianus); 2, metasomal tergum 6 dorsally distinctly expanded, representing the largest metasomal tergum in females (P. dyak). those in the small African yangambicolus species group, which is characterized by a less well-defined mesopleural triangle. Based on this character and other evidence, Ronquist (1995a) treated the yangambicolus group as a genus (Decellea) distinct from Paramblynotus, reverting the previous synonymization of the two genera by Weld (1962). Here we show that the yangambicolus group is deeply nested within Paramblynotus, and therefore the lack of a distinct ventral mesopleural margin in these species must be interpreted as a secondary reversal. In all other liopterids, as well as in ibaliids and Austrocynips, the ventral margin of the mesopleural triangle is irregular and usually not well defined; in the rare cases where the mesopleural triangle is more
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
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Page 3: ABSTRACT The genus Paramblynotus is
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