Burkseus robustus, Perry & Heraty, 2019

Perry, Ryan K. & Heraty, John M., 2019, A Tale of Two Setae: How Morphology and ITS 2 Help Delimit a Cryptic Species Complex in Eulophidae (Hymenoptera: Chalcidoidea), Insect Systematics and Diversity (AIFB) 3 (5), No. 1, pp. 1-23 : 8-10

Molecular— Burkseus

A combined analysis of all four genes plus morphology recovers the proposed four morphospecies in the vittatus group ( Fig. 3 ). Burkseus robustus n. sp. is recovered as sister to the rest of the genus, while B. sigillatus n. sp. is recovered as sister to B. vittatus comb. n. + B. flavoviridis comb. n. The B. vittatus specimens from California were nested amongst the Palearctic and Canadian specimens. Genetic distances within B. flavoviridis , B. sigillatus , and B. vittatus are minimal, even between Nearctic and Palearctic specimens of B. vittatus .

In B. robustus , these are more substantial, with the Colombian and New Mexico specimens more distant from the remaining Nearctic specimens. Despite this, there are no substantial morphological characters that separate the B. robustus specimens. The illustrations of the mesosoma on the combined molecular and morphological tree ( Fig. 3 ) are purposely absent of any color patterns of the morphospecies ( Figs. 4–6 ) to focus solely on the mesosomal setae patterns that quickly differentiate the taxa.

The 28S D2 + D3–5 ML analysis recovers B. sigillatus and B. flavoviridis together as monophyletic (Supp. Fig. S2 [online only]). ITS2 recovers the four hypothesized groups of ingroup species that were based on morphology ( B. sigillatus is only represented by one specimen in this analysis). Burkseus sigillatus (D4738) is recovered as sister to B. vittatus + B. flavoviridis (Supp. Fig. S3 [online only]). In the COI analysis, Burkseus vittatus , B. flavoviridis , and B. sigillatus are monophyletic, but C. robustus is paraphyletic; B. sigillatus (D4738) is sister to B. vittatus (Supp. Fig. S4 [online only]). An analysis of all four gene regions resulted in the two B. sigillatus specimens (lacking ITS2 or COI) identical to B. flavoviridis (Supp. Fig. S5 [online only]). The third B. sigillatus specimen (D4738) was recovered as sister to B. vittatus . Removing the two B. sigillatus specimens lacking COI and ITS2 and performing an additional four-gene analysis results in four monophyletic morphospecies, with B. sigillatus placed as the sister group of B. vitattus although with no bootstrap support (Supp. Fig. S6 [online only]).

The bPTP analysis of all four gene regions, with D5324 and D5325 removed, proposed additional lineages not found in other molecular analyses (Supp. Fig. S7 [online only]). As expected, Burkseus vittatus and B. flavoviridis emerge as the only monophyletic species, while B. robustus was recovered monophyletic but as three species. The single B. sigillatus D4738 specimen with ITS2 and COI was proposed as a species sister to B. vittatus . With ABGD, the COI NJ-MD region results recognized four species (Supp. Fig. S8 [online only]).

Figures

Fig. 3. Combined molecular and morphological maximum likelihood tree.The different symbols correspond with specimens collected at the same location. Each specimen of these groups was collected during the same collecting event, with the exception of D3665, D3666, and D3791, collected at the same location but 2 wk apart.

Fig. 4. Mesosomal color variation in Burkseus flavoviridis: (A) D4682, (B) D4741, (C) D3791 (specimen collapsed while drying), (D) D4593, (E) D4171, F) D4172, (G) D4679, (H) D4683, (I) D4176, (J) D4169, (K) D4175, and (L) illustrated view. Scale bar = 0.2 mm.

Fig. 5. Mesosomal color variation.(A–H) Burkseus robustus: (A) D3674,(B) D3675,(C) D4591,(D) D4580,(E) D4581,(F) D4680,(G) D5326,(H) illustrated view.(I–L) B. sigillatus: (H) D5325, (I) D5324, (J) D4738, and (L) illustrated view. Scale bar = 0.2 mm.

Fig. 6. Dorsal view of mesosomal color variation in Burkseus vittatus: (A) D4559, (B) D5320, (C) D5113, (D) D5101, (E) D4699, (F) D3640,(G) D4173, (H) D3665, (I) D3666,(J) D4177, (K) D3993, and (L) illustrated view. Scale bar = 0.2 mm.

Fig. 2. Fore wings, dorsal view: (A) Burkseus vittatus comb. n., (B) B. flavoviridis comb. n., (C) B. robustus n. sp., (D) B. sigillatus n. sp. The photographs of B. robustus and B.sigillatus were taken after DNA extraction,displaying how the dark colors on the submarginal vein setae (B. robustus and B.sigillatus), stigmal vein and uncus (B. robustus), and banding patterns (B. sigillatus) are resilient enough to remain visible after extraction. Scale bar = 0.5 mm. ams = admarginal setae, bsl = basal setal line, csl = cubital setal line, disc = fore wing disc, spc = speculum, smv = submarginal vein, stg = stigmal vein, unc = uncus.

Fig. 8. Gaster color variation within females (A–E) and males (F–J) of the four Nearctic Burkseus species.