Morphometric analysis and taxonomic revision of Anisopteromalus Ruschka (Hymenoptera: Chalcidoidea: Pteromalidae) - an integrative approach

Abstract

We use an integrative taxonomic approach to revise the genus Anisopteromalus. In particular, we apply multivariate ratio analysis (MRA), a rather new statistical method based on principal component analysis (PCA) and linear discriminant analysis (LDA), to numerous body measurements and combine the data with those from our molecular analysis of Cytb and ITS2 genetic markers (on a subset of species) and all available published data on morphology, karyology, behaviour, host associations and geographic distribution. We demonstrate that the analysis of quantitative characters using MRA plays a major role for the integration of name-bearing types and thus for the association of taxa with names. Six species are recognized, of which two are new: A. cornis Baur sp.n. and A. quinarius Gokhman & Baur sp.n. For Anisopteromalus calandrae (Howard), a well-known, cosmopolitan parasitoid of stored-product pests, we have selected a neotype to foster continuity and stability in the application of this important name. The species was sometimes confused with the related A. quinariussp.n., another cosmopolitan species that is frequently encountered in similar environments. We also show that several species originally described or later put under Anisopteromalus actually belong to different genera: Cyrtoptyx camerunus (Risbec) comb.n.; Meraporus glaber (Szelényi) comb.n.; Dinarmus schwenkei (Roomi, Khan & Khan) comb.n.Neocatolaccus indicus Ayyar & Mani is confirmed as a junior synonym of Oxysychus sphenopterae (Ferrière) syn.n. and Anisopteromalus calandrae brasiliensis (Domenichini) stat.rev. must be considered as a valid but doubtful taxon. This published work has been registered in ZooBank, http://zoobank.org/urn:lsid:zoobank.org:pub:BDFE96D3-D0F4-4012-90F5-9A087F7F5864.

Figure 1

Scatterplot of first against second shape PC of females of all six OTUs of Anisopteromalus. (A, B) Shape PCA, including all 20 variables (A) and with variable gaster breadth omitted (B). Closed symbols: blue dots, A. calandrae; red squares, A. quinarius. Open symbols: violet diamonds, A. apiovorus; green upside down triangles, A. caryedophagus; black circle, A. ceylonensis; orange triangles, A. cornis. In (B), name-bearing types are marked with bold plus signs, the light blue plus sign indicates the position of the neotype of A. calandrae. The variance explained by each shape PC is given in parentheses.

Figure 2

Size and shape analysis of females of OTUs Anisopteromalus calandrae and A. quinarius using all variables except gaster breadth. (A, B) Shape PCA, scatterplot of first against second shape PC (A), scatterplot of isosize against first shape PC (B). Symbols: blue dots, A. calandrae; red squares, A. quinarius; in parentheses the variance explained by each shape PC. (C, D) Ratio spectra, PCA ratio spectrum (C), allometry ratio spectrum (D); horizontal bars in the ratio spectra represent 68% bootstrap confidence intervals based on 1000 replicates.

Figure 3

Shape PCA for exploring female variation within Anisopteromalus calandrae and A. quinarius using all variables except gaster breadth. The analyses included three cultured laboratory strains for each OTU. (A) Scatterplot of first against second shape PC of A. calandrae: cross, strain Bamberg USA; plus signs, strain Savannah USA; open circles, strain Slough (ICSP) UK. (B) Scatterplot of first against second shape PC of A. quinarius: cross, strain Moscow (MSU) Russia; plus signs, strain Michurinsk Russia; open squares, strain Fresno USA. The variance explained by each shape PC is given in parentheses.

Figure 4

ML trees from the analyses of ITS2 and Cytb sequences of several strains of the OTUs Anisopteromalus calandrae and A. quinarius. Bootstrap supports higher than 70% are indicated at nodes. Scale bar indicates substitution per site for both trees.

Figure 5

Diagnostic characters of Anisopteromalus, females. (A, B) Forewing with speculum, A. apiovorus (A; actually the setae are whitish in this species but they appear darkened because of the contrasting background), A. quinarius sp.n. (B); (C, D) mesosoma with scutellum projection in lateral view, A. apiovorus (C), A. calandrae (D); (E, F) proximal funicular segments, A. apiovorus (E), A. calandrae (F); (G, H) gaster in dorsal view with posterior margin of first tergite emphasized with a magenta line, A. calandrae (G), A. quinarius sp.n. (H); (I, J) antenna, A. calandrae (I), A. cornis sp.n. (J); (K, L) mesosoma in dorsal view, A. calandrae (K), A. cornis sp.n. (L). Arrows mark important character states.

Figure 6

Diagnostic characters of Anisopteromalus, females. (A, B) Mesosoma with scutellum shape in lateral view, A. ceylonensis (A; holotype female, original position mirrored and photo slightly modified with Photoshop), A. caryedophagus (B); (C, D) gena near mouth corner in postero-lateral view, A. quinarius sp.n. (C), A. caryedophagus (D); (E, F) median area of propodeum, A. quinarius sp.n. (E), A. caryedophagus (F). Arrows mark important character states.

Figure 7

Diagnostic characters of Anisopteromalus, males. (A–C) Proximal funicular segments, A. calandrae, average-sized specimen (A), the same, small specimen (B), A. quinarius sp.n. (C); (D, E) gaster in dorsal view, A. calandrae (D), A. quinarius sp.n. (E). Arrows mark important character states.