Hymenoptera) with Highly Specialized Egg Morphology
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Systematic Entomology (2011), 36, 529–548 Maxfischeriinae: a new braconid subfamily (Hymenoptera) with highly specialized egg morphology ∗ ∗ CHARLES ANDREW BORING1 , BARBARA J. SHARANOWSKI2 andMICHAEL J. SHARKEY1 1Department of Entomology, S-225 Agricultural Science Center North, University of Kentucky, Lexington, KY, U.S.A. and 2Department of Entomology, 214 Animal Science Bldg., University of Manitoba, Winnipeg, Canada Abstract. The tribe Maxfischeriini, previously placed in Helconinae, is emended to subfamily status based on morphological and biological evidence. Proposed autapomorphies for Maxfischeriinae include: the presence of a pronotal shelf, forewing vein 1a and 2a present, although 1a nebulous, ventral valve of the ovipositor with serrations from tip to base and specialized egg morphology. The novel, pedunculate egg morphology is described for Maxfischeria, representing a new life- history strategy among Braconidae. Based on egg and ovipositor morphology, we suggest that Maxfischeria is a proovigenic, koinobiont ectoparasitoid. Five new species of Maxfischeria Papp are described with an illustrated key to all species (Maxfischeria ameliae sp.n., Maxfischeria anic sp.n., Maxfischeria briggsi sp.n., Maxfischeria folkertsorum sp.n. and Maxfischeria ovumancora sp.n.). In addition to the identification key presented here, all known species of Maxfischeria can be separated using the barcoding region of cytochrome c oxidase subunit I (COI ). Based on molecular data, the phylogenetic relationships among the six known species of Maxfischeria are as follows: (M. folkertsorum sp.n. (M. ovumancora sp.n. (M. briggsi sp.n. (M. anic sp.n. (M. tricolor + M. ameliae sp.n.))))). Introduction in the forewing. However, Maxfischeria does not possess other features associated with Helconini, including a distinct Until now the braconid genus Maxfischeria included a lamella on the frons, two strongly developed lateral carinae single species, Maxfischeria tricolor Papp. In the original on metasomal median tergite 1, a long ovipositor relative description, Papp (1994) provisionally proposed the tribe to the body, a large body size (typically longer than Maxfischeriini within Helconinae for this monotypic genus. 7 mm), and a complete occipital carina. Thus, the similarities Although M. tricolor shares similarities with members of in wing venation, which are plesiomorphic features, are Helconinae, Papp (1994) remarked that ‘in the future the the only characteristics Maxfischeria has in common with tribe would [sic] be emended to subfamily rank considering Helconinae. its features which differentiate it from all other helconine Until recently, Papp’s hypothesis on the placement of Max- genera’ (p. 143). Maxfischeria shares strikingly similar wing fischeria within Helconinae has not been tested. Maxfischeria venation with members of the tribe Helconini, including appears to be a non-cyclostome, having a flat labrum and the relatively complete venation, the presence of forewing vein spiracle of metasomal tergum 2 on the lateral tergite. How- 1RS, and a complete trapezoidal second submarginal cell ever, Sharanowski et al. (2011) recovered a strongly supported basal clade containing Maxfischeria, Aphidiinae and Meso- Correspondence: Barbara J. Sharanowski, Department of Entomol- stoinae. This clade was recovered as sister to all remaining ogy, 214 Animal Science Bldg., University of Manitoba, Winnipeg, cyclostomes. Other multigene analyses have also recovered a MB, Canada R3T 2N2. E-mail: [email protected] basal Mesostoinae + Aphidiinae, providing further evidence for this relationship (Belshaw et al., 2000; Zaldivar-Riveron´ ∗These authors made equal contributions to the article. et al., 2006). Here we examine morphological and biological © 2011 The Authors Systematic Entomology © 2011 The Royal Entomological Society 529 530 C. A. Boring et al. features of Maxfischeria and formally propose Maxfischeriinae and Doryctes sp. (Doryctinae). The choice of out-group was as a new subfamily. Additionally, we describe five new species based on the phylogenetic position of Maxfischeriinae within of Maxfischeria, and redescribe the holotype of M. tricolor the Braconidae, as elucidated in Sharanowski et al. (2011). All Papp to correct previous errors. We also present an identifi- trees were rooted with Doryctes sp. cation key for all species, and infer phylogenetic relationships Sequences were obtained using the protocols outlined below, among the species using molecular data. except for sequences for Aphidius rhopalosiphi and Andesipo- Biological information about Maxfischeria is almost entirely lis sp., which were obtained from GenBank (accession nos unknown. This lack of information is typical for parasitic EU819406 and AY935411, respectively). DNA was extracted Hymenoptera. However, we do find a most unusual egg from ethanol-preserved specimens following Qiagen proto- morphology, which is so striking that it demands further cols in conjunction with the DNeasy™ Tissue Kit (Qia- attention. Maxfischeria have eggs that are stalked with gen, Valencia, CA, U.S.A.). The mitochondrial gene COI an umbrella-like anchor, which are unlike any braconid was amplified using protocols and primers from Schulmeis- egg yet described. These eggs most closely resemble the ter et al. (2002) (COI lco hym 5-CAAATCATAAAGATA specialized eggs of a few Ichneumonidae; however, the eggs TTGG-3 and COI hco outout 5-GTAAATATATGRTGDG of Maxfischeria are unique, and any similarity is convergent. CTC-3). Both product purification and sequencing were Here, we describe this novel egg morphology and make performed at the Advanced Genetic Technologies Center, inferences about the biology of Maxfischeria. University of Kentucky, using Agencourt CleanSEQ mag- netic beads and an Applied Biosystems 3730xl DNA Ana- lyzer, respectively. Contigs were assembled and edited using Material and methods contig express (Vector NTI Advance10™ Invitrogen™). Genbank accession numbers are listed in Table 1. Addi- General morphological terminology follows Sharkey & tional sequenced genes including 28S and 18S rDNA, and Wharton (1997). Additionally, malar space was measured as the protein-coding genes carbamoyl-phosphate synthetase- the shortest possible length from the bottom of the eye to the aspartate transcarbamoylase-dihydroorotase (CAD) and acetyl- most basal region of the mandible from an anterior view. Ten- coenzyme A carboxylase (ACC ), were uninformative for torial length was taken as the shortest distance between the species-level relationships for Maxfischeria (data not shown). outer circular margins of the anterior tentorial pits from an We also attempted amplification of the internal transcribed anterior view. All specimens of Maxfischeria were collected in spacer 1 of the rDNA array and the mitochondrial gene Australia, stored in 95% ethyl alcohol and dissected in the same cytochrome c oxidase subunit II without success. solution. Photographs were made with gt entovision® soft- Alignment was performed using muscle (Edgar, 2004) on ware using a JVC KY-F75 3CCD digital camera. All mounted the European Bioinformatics Institute (EBI) server. Read- specimens were chemically dried using hexamethyldisilazane ing frame accuracy was checked with mega 4.0.2 (Tamura (HMDS), following the protocol of Heraty & Hawks (1998). et al., 2007) using the invertebrate mitochondrial genetic code. For scanning electron microscopy (SEM), specimens were Nucleotide frequencies and measures of genetic distance were dried with HMDS, coated with gold palladium, and images calculated with mega 4.0.2 (Tamura et al., 2007). The χ 2 test were taken with a Hitachi S-800 scanning electron microscope. for homogeneity in base composition was used to test for biases Measurements were taken with a digital micrometer using a across taxa using paup* (Swofford, 2000). To explore the pos- Leica MZ12-5 stereoscope. All specimens were compared with sibility for saturation in the Maxfischeria dataset, pairwise the holotype of M. tricolor. Tajima–Nei distances (1984) were plotted against the abso- lute number of transitions and transversions for each codon position. Phylogenetic analysis Parsimony and Bayesian analyses were performed using tnt 1.0 (Goloboff et al., 2003) and mrbayes 3.1.2 (Huelsen- Initially, 14 specimens, representing all six known species beck & Ronquist, 2001; Ronquist & Huelsenbeck, 2003), of Maxfischeria, were chosen for phylogenetic analysis using respectively. For both reconstruction methods, the dataset was the mitochondrial gene cytochrome c oxidase subunit I (COI ). analysed with all characters included, and with the third posi- However, of the 14 sequences, eight were discovered to be tion excluded. Additionally, different sets of out-group taxa nuclear-based copies of mitochondrial sequences, or NUMTs were analysed to explore the effect of out-group choice on (Lopez et al., 1994), based on several criteria outlined by phylogenetic inference. For each parsimony analysis, tree Zhang & Hewitt (1996). Thus, the eight NUMT sequences searching was performed with implicit enumeration with 1000 were not used in the analyses, but were submitted to GenBank bootstrap replicates. Strict consensus trees were calculated (accession nos HQ836369–HQ836375). The final phylogenetic when more than one tree of minimum length was recovered. analysis included six Maxfischeria sequences, representing all For the Bayesian analyses, the general time-reversible model six known species (Table 1). An additional three species were with a parameter for invariant sites (GTR