Vladelektra blagoderovi Evenhuis, 2020

Evenhuis, Neal L., 2020, Vladelektra, an enigmatic new genus of killer fungus gnats (Diptera: Keroplatidae: incertae sedis) from mid-Cretaceous Burmese amber., Bishop Museum Occasional Papers 139, pp. 1-9 : 3-8

Vladelektra blagoderovi Evenhuis , sp. nov.

( Figs. 1–7 )

Type material. Holotype male (BPBMENT 0000016434) and paratype female (BPBMENT 0000016435) from MYANMAR: Kachin State: Hukawng Valley in the same amber piece. Other paratype: a separate amber piece with male ( BPMENT 0000016436 ) from same locality. The amber pieces containing the holotype and paratypes are deposited in the entomological collection of the Bernice Pauahi Bishop Museum, Honolulu, Hawai‘i, USA.

Etymology of genus and species epithets. The generic (combining Vlad + the Greek ^λέκτρα “elektra ” = “amber”) and specific names honor my good friend and colleague Vladimir Blagoderov for his significant contributions to fossil dipterology and for increasing our knowledge of Sciaroidea.

Diagnosis. As for genus.

Description. Male. Based on two specimens, each with head, legs and abdomen cleared internally. Lengths: Body: 2.2–2.3 mm; wing: 1.5–1.6 mm. (Habitus Fig. 2 ). Head. Occiput and frons pale brown. Face and clypeus dark brown. Eyes without inter-ommatidial setae; facets of two sizes, upper half of eye with larger ommatidia than lower half. Ocelli not discernable due to opacity of head capsule. Palp ( Fig. 3 ) moniliform, three-segmented, each segment lozenge-shaped, subequal in length, apicalmost segment setose on apical half, with subapical palpal pit. Antennae ( Fig. 4 ): brown, scape and pedicel discoid. Flagellum: 14 segments; segments 1–4 cylindrical, ca. two times longer than wide; segments 5–14 length subequal to width; terminal segment (14) subconical.

Thorax. Dark brown. Notum with sparse long hairs irregularly arranged. Scutellum with long hairs at apex. Pleura brownish black (vestiture not viewable). Halter stem pale brown, knob brown.

Legs. Brown. Coxae long, all same length. Hind femur with yellow color basoventrally and thin yellow stripe ventrally on basal two-thirds. Tibiae with trichia not arranged in rows. Tibial spurs long: 1: 2: 2. Tibial length 1.25 times femoral length; basitarsus length 1/2 length of tibia. Tarsi shorter than body length. Claws minute.

Wing ( Fig. 5 ). Hyaline. Costa with minute spicules along entire length; microchaetae on R 1, all other veins bare. Costa ends beyond end of R 4+5 two-thirds distance to end of M 1. Sc incomplete. R 2+3 ending in C two-thirds distance from end of R 1 to end of R 4+5. Base of M 1 and M 2 effaced, junction of M 1 and M 2 faintly evident. M 4 effaced at base, curved downward on apical fourth. CuA complete, curved downward at apical one-fourth. CuP absent. Alula reduced.

Abdomen. Brown with spot of yellow at posterolateral corner of each tergite. Long, thin, slightly dorso-ventrally compressed, with sparse hairs dorsally, laterally, and ventrolaterally.

Genitalia ( Fig. 7 ) Gonocoxa linear-conical, long, thin. Gonostylus long, thin, tapering to darkly sclerotized bifid apical one-fifth, with short setae along dorsal surface, other short setae subapically on ventral surface. Tergal apodeme short, narrow, slightly flared basally. Epandrium subquadrate, slightly tapered to apex, ca. two times longer than basal width, with rounded apex, and patch of minute villi on apical fifth.

Female. As in male except lack of vein R 2+3 (cf. Fig. 6 ) and shorter antennae (cf. Fig. 4 ). Basal connection of veins M 1 and M 2 not effaced; vein M 1 not reaching wing margin.

Remarks. The close proximity of the tips of the abdomens of the holotype male and paratype female lead to the possibility that they became trapped while in copula and separated during their struggle to escape.

DISCUSSION

Vladelektra intriguingly exhibits features of both Keroplatidae (s. str.) (wing venation) and the former Lygistorrhinidae [now a subfamily within Keroplatidae (teste Matic et al. 2020)] (male genitalia with tergal apodeme). Although lacking a well developed proboscis as in many lygistorrhinids ( Seguyola Matile, 1990 also lacks them) and possessing male genitalia reminiscent of many lygistorrhinids, especially in the presence of the tergal apodeme (see Fig. 6 ), the wing venation with effaced basal portions of medial and cubital veins, and the presence of R 2+ 3 in the male (although lacking in the female) would seem to better place Vladelektra within Keroplatidae (s. str.) for now. The radial-medial fusion (characteristic of Keroplatidae ) that is not seen in this species could be there, but is not discernable due the effaced base of the medial veins. The dimorphism between males and females is most striking in the presence (males) or absence (females) of R 2+3 and also evident in the differences in length of the antennae and in shape of the antennal flagellomeres (cf. Fig. 4 ).

Within Keroplatidae (s. str.), the specimens appear similar in some respects to the extant Afrotropical Asynaphleba Matile, 1974 (both having 14-segmented flagellomeres; short R 2+3, and moniliform palpal segments). However, it is clearly not that genus based on the presence of CuP (absent in Vladelektra ), and R 2+3 ending in C closer to the end of R 1 than R 4+5 (ending closer to R 4+ 5 in Vladelektra ). Additionally, Asynaphleba has a distinct stem of M, base of M 4, and m-cu, all of which are effaced in Vladelektra .

Vladelektra gen. nov. is also similar to the keroplatine Papuan and Oriental Xenokeroplatus Matile, 1981 in wing venation (especially effaced bases of medial vweins) and lacks vein CuP, which characterizes the latter genus among Keroplatini in those keys, but (besides having three instead of two palpal segments) Vladelektra differs in having legs much shorter (tarsi longer than body length in Xenokeroplatus ), external tibial spurs present (absent in Xenokeroplatus ), shorter mediotergite (more pronounced in Xenokeroplatus ), male antennal flagellomeres more cylindrical (compressed and shorter in overall length in Xenokeroplatus ), and distinctly different male genitalia with tergal apodeme present (absent in Xenokeroplatus ).

Blagoderov & Arillo (2002) described a keroplatid, Hegalari Blagoderov & Arillo, 2002 from the Lower Cretaceous amber of Alava, Spain that also lacks vein CuP. They were unsure of the placement of the genus within the family, but its features were most similar to those belonging to Macrocerinae . Hegalari is not the same as Vladelektra in that the antennae of the type species, Hegalari antzinako Blagoderov & Arillo , are somewhat compressed and the overall length is much shorter than those in males of Vladelektra (probably due to the type of H. antzinako possibly being a female). However, the second species described in that paper, Hegalari minor , is much more similar to Vladelektra and has much longer antennae with more cylindrical flagellomeres as in Vladelektra males and slightly different wing venation than H. antzinako and might be better removed to a separate genus. Vladelektra differs from H. minor in having R 4 closer to the apex of the wing than in H. minor , the base of M 1 effaced (present in H. minor ), and the apicalmost male flagellomere length subequal to width (two times as long as wide in H. minor ).

This marks the third described species of Keroplatidae from Burmese amber ( Guo et al. 2017 [species of which are treated in Mycetophilidae ]; Ross 2019). Cockerell (1917) described Burmacrocera (now placed in Orfeliini ). Ševčík et al. (2020) described a second species (in the new genus Adamacrocera) belonging to a new putative primitive subfamily with similarities to Macrocerinae .

Figures

Fig. 1. Amber piece containing type specimens of Vladelektra blagoderovi Evenhuis, gen. nov. et sp. nov. Abbreviations: H = holotype male; P = paratype female.

Fig. 2. Vladelektra blagoderovi Evenhuis, sp. nov., a. male holotype and female paratype in situ. b. male paratype in situ.

Fig. 3. Vladelektra blagoderovi Evenhuis, sp. nov., lower portion of male head showing palpi and eye divided into upper and lower ommatidia. a. in situ. b. illustration to clarify structures.

Fig. 4. Vladelektra blagoderovi Evenhuis, sp. nov., antennae: male above, female below, both to scale. Abbreviations: I = flagellomere I; pe = pedicel.

Fig. 5. Vladelektra blagoderovi Evenhuis, sp. nov., male wing. a. in situ. b. illustration to clarify venation. c. detail of wing base showing effaced veins.

Fig. 6. Vladelektra blagoderovi Evenhuis, sp. nov., female wing showing effaced medial vein and lack of vein R2+3.

Fig. 7. Vladelektra blagoderovi Evenhuis, sp. nov., male genitalia. Abbreviations: ep = epandrium; gx - gonocoxa; gs = gonostylus; ta = tergal apodeme.