Previously, the only published phylogenetic analysis of Dryinidae was a morphological analysis of just 32 characters. Herein, I present the first analysis of molecular sequence data examining the relationships among several of the major subfamilies of Dryinidae. A total of 77 specimens of Dryinidae from seven subfamilies, two specimens of Chrysis (Chrysididae), one specimen of Cleptes (Chrysididae), and one specimen of Sclerogibba (Sclerogibbidae) were examined utilizing molecular sequence data from nuclear 18S and 28S genes and mitochondrial Cytochrome Oxidase Subunit I (COI) and Cytochrome b (Cytb) genes. Dryininae were rendered nonmonophyletic due to the placement of Thaumatodryinus, which was sister to the remainder of Dryininae and Gonatopodinae. To establish monophyly of Dryininae, Thaumatodryininae were resurrected for Thaumatodryinus.

Pincer Wasps, Molecular Systematics, Phylogeny, Phylogenetics

Dryinidae are the third largest family within Chrysidoidea, containing 15 subfamilies, 50 genera, and over 1700 species found worldwide (Olmi 1994b, Olmi and Virla 2014, Olmi et al. 2014). These wasps are parasitoids and predators of Auchenorrhyncha and have huge potential as agricultural biocontrol agents, particularly for rice, fruit, and sugarcane pests (Sahragard et al. 1991, Olmi 1989, Mora-Kepfer and Espinoza 2009, Virla et al. 2011). In one species, Gonatopus flavifemur Esaki & Hashimoto, 1932, a single female was recorded as having attacked 466 planthoppers (as both food and hosts) over its 19-day adult life (Chua and Dyck 1982, Sahragard et al. 1991). Most dryinid species are host generalists that attack a wide variety of Auchenorrhyncha, often with host species belonging to different genera or even different families (Guglielmino and Olmi 1997, Guglielmino et al. 2013).

With only one or two world experts exclusively studying Dryinidae at any one time, the family has an interesting, but sparse, taxonomic history. Kieffer (1914) wrote the first world monograph of Dryinidae, with the first revisionary taxonomy for the family coming from Richards (1939, 1953). Outside of small agricultural studies and taxonomic descriptions, there was little focus on Dryinidae until the publication of Olmi (1984), a 1913-page world monograph that revised much of the taxonomy and provided keys throughout the family. Since then, there has been a growth in known dryinid diversity and host-records and the production of several large regional monographs (Olmi 1994a, b, Olmi 2005, Olmi 2007, Xu et al. 2013, Olmi and Virla 2014).

Currently, the fifteen subfamilies consist of four fossil subfamilies: BurmadryininaeOlmi et al., 2014, Palaeoanteoninae Olmi & Bechly, 2001, Ponomarenkoinae Olmi 2010, and Protodryininae Olmi & Guglielmino, 2012 – and eleven extant subfamilies: Anteoninae Perkins, 1912, Aphelopinae Perkins, 1912, Apoaphelopinae Olmi, 2007, Apodryininae Olmi, 1984, Bocchinae Richards, 1939, Conganteoninae Olmi, 1984, Dryininae Haliday, 1833, Erwiniinae Olmi & Guglielmino, 2010, Gonatopodinae Kieffer, 1906, Plesiodryininae Olmi, 1987, and Transdryininae Olmi, 1984. The five largest subfamilies, Anteoninae, Gonatopodinae, Dryininae, Bocchinae, and Aphelopinae are found worldwide and comprise over ninety percent of the known diversity of Dryinidae (Olmi and Virla 2014, Xu et al. 2013). Conganteoninae contains about 15 species found in the Palearctic, Afrotropical, and Oriental regions, Plesiodryininae are known from a single species in the Nearctic region, Erwiniinae are known from a single species in the Neotropical region, Apoaphelopinae are known from two species in South Africa and Mozambique, Apodryininae are known from 13 species (with a Gondwanan distribution) and Transdryininae are known from two species from Australia (Olmi 1984, Olmi and Guglielmino 2010, Xu et al. 2013, Olmi and Virla 2014).

Over half of the described species of Dryinidae are found within three genera–Anteon Jurine, 1807, Dryinus Latreille, 1804, and Gonatopus Ljungh, 1810. A multiplicity of genera were synonymized within these three (refer to Olmi and Virla 2014 and Xu et al. 2013 for a complete list), but only within Gonatopus and Dryinus were the synonymized genera delimited amongst species groups. Olmi (1993) first synonymized Chelothelius Reinhard, 1863, Mesodryinus Kieffer, 1906, Perodryinus Perkins, 1907, Tridryinus Kieffer, 1913, Bocchoides Benoit, 1954, and Alphadryinus Olmi, 1984 within Dryinus and Dicondylus Haliday, 1830, Pseudogonatopus Perkins, 1905, Agonatopoides Perkins, 1907, Apterodryinus Perkins, 1907, Donisthorpina Richards, 1939, Plectrogonatopoides Ponomarenko, 1975, and Acrodontochelys Currado, 1976 within Gonatopus based on the lack of genus-level synapomorphies in the males of these synonymized genera. Trichogonatopus Kieffer, 1909 was also synonymized with Gonatopus upon the discovery of male specimens in Virla et al. (2010). Olmi (1993), Xu et al. (2013), and Olmi and Virla (2014), provided morphological keys to describe four species groups within Dryinus and 12 in Gonatopus.

Olmi (1993) also synonymized Thaumatodryininae Perkins, 1905 as a genus within Dryininae, Thaumatodryinus Perkins, 1905, along with moving a Gonatopodinae genus, Pseudodryinus, Olmi 1989, to Dryininae on the basis of mandibular character similarity in males. Currently, males of both Pseudodryinus and Thaumatodryinus are distinguishable from the other genera in Dryininae by having quadridentate mandibles, with Thaumatodryinus males presenting mandibular teeth that usually progress larger from anterior to posterior, whereas in Pseudodryinus, the four teeth of the mandible are irregularly sized. Females of Thaumatodryinus are easily distinguished from other Dryininae by the presence of long hairs on flagellomeres 3 – 8 (Mita 2009, Xu et al. 2013).

There is very little published on the phylogenetic relationships of the subfamilies within Dryinidae. Olmi (1994a) stated “we cannot discuss species affinities, because evolution has followed completely different paths in males and females, and female affinities are completely different from male affinities”, and did not attempt to combine morphological data from both sexes to reconstruct a phylogeny. Olmi (1994a) presented a tree, but only included female specimens from four subfamilies found within Denmark and Fennoscandia and did not make clear how characters were coded and analyzed. In Carpenter (1999), a cladogram was reconstructed from 32 characters based on the taxonomic keys and descriptions of Massimo Olmi from both sexes. Given the growth in known dryinid diversity since then, neither study reflects the current subfamily classification and only addressed a small number of morphological features, although both placed Aphelopinae as the basal subfamily of Dryinidae and placed Gonatopodinae and Dryininae as sister groups (as in Olmi 1994a) or as closely associated in a polytomy that also contained Transdryininae and (Apodryininae + Plesiodryininae) (Carpenter 1999). There are no published molecular phylogenies, but DNA has been used to link the highly modified females of Gonatopus javanus Perkins, 1912 to males, which are similar looking throughout the genus, and to explore intraspecific genetic variation (Mita and Matsumoto 2012, Mita et al. 2013). Herein, I present the first analysis of molecular sequence data examining the relationships among several of the major subfamilies.

The topologies of the equal weighting and implied weighting analyses in TNT (parsimony) were the same, with the equal weighting analysis recovering nine trees with a best score of 8562 steps (CI 0.287 RI 0.641) and the implied weighting (K = 20.527) analysis recovering nine trees with a best score of 200. The best RAxML tree from 20 separate analyses had a final optimization likelihood of -44251.166938 (Fig. 2), and had the same topology as the tree produced by Garli, and the MrBayes analysis produced an average standard deviation of split frequencies (ASDSF) of 0.010179, with 25 percent of samples discarded as burn-in (Fig. 3).

Results were largely congruent for parsimony, likelihood, and Bayesian approaches in terms of higher-level topology (Figs 1–3), while species-level topologies were more variable. Apodryininae (as represented by Madecadryinus politus Olmi, 2007) were the sister taxon to all other Dryinidae in every analysis. The greatest difference among analyses were among Aphelopinae, Bocchinae and Conganteoninae. In all three trees, Aphelopinae and Conganteoninae were recovered as monophyletic, but since Bocchinae were represented by one species, its monophyly could not be tested. In the Bayesian analysis, Bocchinae were the sister group to the remainder of Dryinidae excluding Apodryininae, with Aphelopinae and Conganteoninae as sister groups. In the parsimony and likelihood analyses, Bocchinae were the sister group to Conganteoninae, with Aphelopinae sister to (Conganteoninae + Bocchinae). The remaining subfamily topologies were the same in all three analyses – Anteoninae, Aphelopinae, and Gonatopodinae were monophyletic, with Anteoninae as the sister subfamily to ((Thaumatodryinus + (Dryininaepartim + Gonatopodinae). Dryininae were paraphyletic due to the placement of Thaumatodryinus merinus Olmi, 2004 and Thaumatodryinus macilentus De Santis & Vidal Sarmiento, 1974, which were sister to a monophyletic Gonatopodinae and the remainder of Dryininae.

Figure 1. 

Parsimony support tree. Jackknife support for nodes given in GC-values (frequency differences) from 1000 replicates. CI 0.287 RI 0.641. Scale bar in all images is 1.0 mm.

Figure 2. 

Likelihood support tree. Rapid Bootstrap support values shown at nodes.

Figure 3. 

Bayesian support tree. Support probabilities shown at nodes as a percent.

Many of the genera tested were found to be nonmonophyletic. Within Anteoninae, Lonchodryinus Kieffer, 1905 was the only genus found as monophyletic, as was Epigonatopus Perkins, 1905 in Gonatopodinae. Dryinus and Thaumatodryinus were the only genera from Dryininae tested, although all four of the Dryinus ‘species groups’ defined by Olmi (1993), were examined. Species groups were only defined for females, so undescribed male dryinid specimens could not be assessed. However, Dryinus Group 1 was found nonmonophyletic due to the placement of Dryinus striatus Fenton, 1927, although Dryinus Group 2 and Dryinus Group 4 were monophyletic. Dryinus Group 3 could not be assessed due to the sampling of a single specimen. Gonatopus was not monophyletic, nor were any of its species groups.

In all analyses, Thaumatodryinus was well-supported and Thaumatodryininae were resurrected here, bringing the total subfamilies of Dryinidae to 16.

The validity of species groups within Dryinus and Gonatopus remains questionable. Some species groups, like Dryinus Group 4, which was originally a separate genus, Perodryinus, were easily recovered as monophyletic while Dryinus Group 1, which contains several synonymized genera, was not recovered as monophyletic. This may be because the larger species groups share synonymized genera – for example, Dryinus species groups 1, 2, and 3 all contain synonymized species from Mesodryinus. Shared synonymized genera are found within the Gonatopus species groups as well.

In continuing molecular studies, specimens from each of the species groups of Gonatopus and Dryinus should be included, as well as all of the genera of the subfamilies, where sampling permits. In particular interest would be to find morphological synapomorphies at the generic level for male Dryinidae.

Thanks are due to Massimo Olmi for help over the past few years in providing specimens, manuscripts, and advice. Thanks as well to James Carpenter, Toshiharu Mita, Jongok Lim, Marcio Oliveira, Pierre Tripotin, the Canadian National Collection, the California Academy of Sciences, and the American Museum of Natural History. The constructive criticism and suggestions of the reviewers were also greatly appreciated.