Janzenella theia Bremer & Talamas, 2021

Bremer, Jonathan, van de Kamp, Thomas & Talamas, Elijah J., 2021, Janzenella theia Bremer & Talamas (Platygastroidea, Janzenellidae): a new species from Baltic amber, Journal of Hymenoptera Research 87, pp. 223-233 : 223

Janzenella theia Bremer & Talamas sp. nov.

Description.

Width of head decreasing anteriorly, occiput in dorsal view strongly excavated, lateral ocellus separated from inner orbit by approximately one ocellar diameter, compound eye relatively large, its length approximately 0.75 that of the head in lateral view; interorbital space broad, approximately equal to height of compound eye; mesoscutum 1.3 times wider than long; femoral depression shallow, weakly defined; forewing with R straight basally, curving toward anterior margin in distal third, R separated from costal margin by at least the width of the vein, r-rs (stigmal vein) straight, much longer than wide (>3 ×); 1Rs, 1Rs+1M, 2Rs, M, and Cu present as spectral veins; propodeum with coarse rugae radiating from propodeal foramen.

Material examined.

Holotype female, USNMENT01223652 (Hoffeins #0002-7), Kaliningrad, Russia, coll. Yantarny, 2015 (deposited in Senckenberg Deutsches Entomologisches Institut, Müncheberg, Germany).

Diagnosis.

Janzenella theia differs from J. innupta in just a few notable characters. The compound eyes of J. theia are significantly larger than those of J. innupta , occupying most of the lateral head (compare Figures 5 , 6 ). Janzenella theia also lacks the pronounced genal swelling that gives the head a quadrate appearance in J. innupta . In the forewing of J. theia , R is separated from the wing margin by at least the width of the vein, and r-rs is much longer than wide (>3 ×) (Figures 2 , 10 ), contrasting that of J. innupta in which R reaches the costal margin and the length of r-rs is about equal to its width (Figure 9 ). The propodeum of J. theia has coarse rugae radiating from the propodeal foramen (Figure 12 ) whereas J. innupta has rugose-areolate sculpture with submedian smooth patches (Figure 11 ).

Etymology.

The species is named after Theia, the mythical Greek titaness of sight, who is credited with endowing precious stones with their brilliance and intrinsic value. The name is treated as an appositional noun.

Discussion.

Janzenella theia and J. innupta are remarkably similar (compare Figures 1 - 4 to 18, 19) given the span of time between the Eocene and the present, as is evidenced by the brevity of our species description and length of the generic description. This similarity, and the conspecificity of J. innupta specimens in Dominican amber and from Costa Rica ( Masner and Johnson 2007), support the notion that morphological change occurs very slowly in Janzenella . We included two characters in our generic description that were assessed in only one of the species. The tibial spurs in Janzenella innupta are very small and required use of high magnification microscopy to confidently assess their number (Figures 16 , 17 ), we were not able to determine their number on J. theia , but given that a 1-2-2 tibial spur formula is plesiomorphic for the superfamily ( Chen et al. 2021), we consider it reasonable to believe that the older species has the same configuration. The pro-, meso- and metafurcae are clearly visible in the reconstructions of J. theia (Figures 13 , 14 ) but we have not yet examined these structures in J. innupta . Given the similarity of J. theia and J. innupta , we treat these characters as stable within Janzenella for the purposes of comparative analysis.

Metanotum. The lateral metanotum in J. innupta (Figure 11 ) is rugose in addition to the line of foveae along the posterior part of the sclerite. Such sculpture on this part of the metanotum (metanotal trough in taxa where the metascutellum is visible) is otherwise unknown to us in Platygastroidea . We were not able to resolve this detail in the rendered images of J. theia .

Profurca. Vilhelmsen et al. (2010) found the profurcal bridge to be absent in Platygastroidea , although it has since been found to exist in the platygastrid genus Amitus Haldeman ( Mikó et al. 2021). The absence of the profurcal bridge in Janzenella is congruent with treating this as a plesiomorphic condition, although internal characters have yet to be examined in the recently erected families Geoscelionidae , Proterosceliopsidae , and Neuroscelionidae ( Talamas et al. 2019; Chen et al. 2021).

Mesofurca. Mikó et al. (2007) reported the presence of a mesofurcal bridge in Scelionidae , which at that time contained lineages now treated as Nixoniidae and Sparasionidae ( Chen et al. 2021). Mikó et al. (2021) reported two forms in Platygastridae : without a bridge in Amitus and with a bridge in Synopeas Förster. Heraty et al. (1994) determined the mesofurcal bridge to be absent in Platygastridae based on examination of two genera ( Isocybus Förster and Inostemma Haliday) and considered that these losses were apomorphies. The absence of a mesofurcal bridge in J. theia thus may indicate close relation to Platygastridae , as was suggested by the analyses of Chen et al. (2021). However, the presence of a mesofurcal bridge in Synopeas reflects the need for greater taxon sampling in Platygastridae to confidently establish the plesiomorphic condition for Platygastridae and to determine if loss of the mesofurcal bridge is indeed irreversible as Heraty et al. (1994) suggested.

Figures

Figures 5 - 8. 5 Janzenella innupta (OSUC 264384), head, anterior view 6 J. theia (USNMENT 01223652), head, anterior view 7 J. innupta (OSUC 264384), head, dorsal view 8 J. theia (USNMENT 01223652), head, dorsal view.

Figures 1, 2. Janzenella theia (USNMENT 01223652), head, mesosoma, metasoma, brightfield photography 1 dorsolateral view 2 ventrolateral view.

Figures 9 - 12. 9 Janzenella innupta (OSUC 264400), fore and hind wings, dorsal view 10 J. theia (USNMENT 01223652), fore and hind wings, ventral view 11 J. innupta (OSUC 264384), mesosoma, dorsolateral view 12 J. theia (USNMENT 01223652), mesosoma, posterodorsal view.

Figures 3, 4. Janzenella theia (USNMENT 01223652), head, mesosoma, metasoma 3 lateral view 4 anterolateral view.

Figures 13 - 17. 13 Janzenella theia (USNMENT 01223652), profurca, posterior view 14 J. theia (USNMENT 01223652), mesofurca, posterior view 15 J. theia, metafurca, posterior view 16 J. innupta (OSUC 264397), mesotibia, lateral view 17 J. innupta (OSUC 264397), metatibia, lateral view.