Monogedania clunipes (Loew) Szadziewski & William L. Grogan & Sontag & Bojarski, 2022

Szadziewski, Ryszard, William L. Grogan, Jr., Sontag, Elżbieta & Bojarski, Błażej, 2022, A new genus of predatory midge in the Monohelea complex from Eocene Baltic amber (Diptera: Ceratopogonidae), Insecta Mundi 2022 (919), pp. 1-9 : 2-8

Monogedania clunipes (Loew) , new combination

Ceratopogon clunipes Loew 1850: 30 (male; Baltic amber); Meunier 1904: 234 (male; Baltic amber). Monohelea clunipes: Szadziewski 1988: 127 (combination; male, female; Baltic amber); Szadziewski 1993: 631 (female

redescribed; Baltic amber of Bitterfeld, Germany); Sontag and Szadziewski 2011: 790 (new record; Baltic amber from

Rovno, Ukraine). Monohelea sp. A : Szadziewski 1988: 131 (male; Baltic amber).

Fig. 1–3G–H

Description. Female ( Fig. 1B ). Body length 1.6–2.3 mm; wing length 1.1–1.5 mm. Proximal flagellomeres cylindrical. Proboscis relatively long, palpus 5-segmented, segment 3 slender without sensory pit. Scutellum with more than 10 long marginal setae. Foreleg, midleg slender, hind leg greatly swollen. Claws of foreleg, midleg short, equal-sized, with basal inner tooth. Hind leg with single very long claw (longer than tarsomere 5), with a short basal inner tooth. Wing with both first radial cells well developed, apex with macrotrichia. Seminal capsules not visible. Male ( Fig. 1A , 2 , 3G–H ). With more dense elongate setae than in female. Body length 1.82 mm; wing length 1.3–1.4 mm. Flagellar plume well developed ( Fig. 2A–B ). Scutum with numerous, stout setae ( Fig. 1A , 2A ). Foreleg, midleg slender; hind leg with greatly swollen femur, tibia and tarsomeres 1–3; femora, tibiae with numerous stout setae; hind tibial comb with very stout spines; hind tarsomere 1 moderately short, swollen, with a single row of stout palisade setae ( Fig. 2C ); tarsomeres 4 elongate, cylindrical; tarsomeres 5 greatly elongate, very slender. Claws small, simple, equal sized on all legs. Wing with macrotrichia on apex. Genitalia stout, short, inverted 180 o ( Fig. 2D–F ). Sternite 9 with distinct caudomedian excavation. Tergite 9 tapering abruptly distally to narrow bilobed apex ( Fig. 3H ). Gonocoxite short, stout. Gonostylus narrowly triangular, broad at base, gradually tapering distally to blunt apex. Aedeagus ( Fig. 2E–F , 3G ) entire with distinct broad basal arch; with two sub-medial caudally directed projections, one median ventrally directed spine-like projection ( Fig. 2E–F , 3G ).

Discussion. This new genus is distinct in having males with dense coarse thoracic setae, a greatly enlarged hind tarsomere 1, extremely slender tarsomeres 5, and an entire aedeagus that is arch-like. In the genera included in the Monohelea complex by Wirth and Grogan (1988), males have a greatly modified ventral plate traditionally called the aedeagus ( Fig. 3A–H ). However, in Ceratopogonidae and other genera of Culicomorpha, the true aedeagus with a gonopore is membranous and located above the sclerotized ventral plate ( Sinclair et al. 2007).

The aedeagus (ventral plate) is composed of a proximal and distal piece in Allohelea ( Fig. 3A ); composed of two lateral pieces with a basal loop in Monohelea ( Fig. 3C ); it lacks a basal loop in Isthmohelea ( Fig. 3B ); it is single, plate-shaped with two sub-median projections in Downeshelea ( Fig. 3E ); it is single, arch shaped, with a single apical median projection in Austrohelea ( Fig. 3D ); it is single, arch shaped with two apical sub-median projections in Schizohelea ( Fig. 3F ), and, in the new genus Monogedania ( Fig. 3G ). Apparently, Monogedania is most similar to Schizohelea in having a similarly shaped arch-like aedeagus with two apical sub-median projections ( Fig. 3F ). However, these two genera differ by seven other characters in Table 1.

Monohelea baltica Szadziewski (1988: 130) described from males in Eocene Baltic amber with an entire aedeagus, and relatively slender hind legs armed with short equal-sized claws that we herein assign to the Holarctic genus Schizohelea , as previously suggested by Szadziewski (1988). The single female MAIG 5624 now determined as Schizohelea baltica ( Fig. 4 ) confirms the new generic position of this species which was originally described from males. This female is very small (wing length 0.67 mm), like males; the wing membrane lacks macrotrichia; tarsomeres 4 are subcylindrical, hind leg tarsomere 5 with ventral basal swelling and hind claw single with long basal tooth ( Fig. 4C ). The wing membrane without macrotrichia and ventral swelling at the base of female tarsomere 5 are unique characters of the genus Schizohelea ( Table 1).

The Monohelea complex now includes 232 extant and two fossil species assigned to the following seven genera:

Allohelea Kieffer, 1917 , worldwide, 62 extant species ( Borkent and Dominiak 2020).

Austrohelea Wirth and Grogan, 1988 , nine extant species from Argentina, Chile, Australia and New Zealand. Schmidt et al. (2018) reported an enigmatic specimen of the genus Austrohelea (sex unknown, no description or illustration) from Oligocene/Miocene amber of New Zealand.

Downeshelea Wirth and Grogan, 1988 , worldwide, 60 extant species ( Santarém et al. 2019; Borkent and Dominiak 2020).

Isthmohelea Ingram and Macfie, 1931 , one extant species from Chile.

Monogedania Szadziewski, Grogan, Sontag and Bojarski , new genus, one Baltic amber fossil species.

Monohelea Kieffer, 1917 , worldwide, 94 extant species.

Schizohelea Kieffer, 1917 , Holarctic, six extant species, one fossil species in Eocene Baltic amber ( S. baltica ( Szadziewski, 1988) , new combination).

In the material examined, one male of Monogedania clunipes has an extended membranous portion of the aedeagus that resembles a penis ( Fig. 2E–F ). However, in all other biting midges, sperm is transferred by spermatophores, but, their membranous aedeagi with a genital pore is not eversible ( Sinclair et al. 2007). We suggest that this is an exceptional case within flies that produce spermatophores when the aedeagus is everted. However, an alternative explanation is possible, as it may be an artefact of fossilization wherein the distal tube of the male genital tract was unnaturally everted in liquid amber.

Figures

Figure 1. Monogedania clunipes (Loew, 1850). A) Male, from collection of Artur Michalski. B) Female, MAIG 2109.

Figure 2. Male of Monogedania clunipes. A) Lateral aspect, MAIG 6010. B) Head and antenna, MAIG 5621. C) Hind tarsi, MAIG 6010. D) Abdomen with inverted genitalia, MAIG 5621. E–F) Lateral views of genitalia, photograph (E), illustration (F), MAIG 6694. Abbreviations: aed–aedeagus, gst–gonostylus, gx–gonocoxite, par– parameres, st 9–sternite 9, tg 9–tergite 9,?–penis.

Figure 3. Male genitalia of genera in the Monohelea complex. A) Aedeagus of Allohelea israelensis Szadziewski and Alwin-Kownacka, 2016 in Alwin-Kownacka et al. (2016), redrawn from Alwin-Kownacka et al. (2016). B) Aedeagus of Isthmohelea disjuncta Ingram and Macfie, 1931, redrawn from Wirth and Grogan (1988). C) Aedeagus of Monohelea mediterranea Szadziewski et al., 2020, redrawn and modified from Szadziewski et al. (2020). D) Aedeagus of Austrohelea shannoni (Wirth and Blanton, 1972), redrawn and modified from Ronderos et al. (2017). E) Aedeagus of Downeshelea stonei (Wirth, 1953), redrawn from Wirth and Grogan (1988). F) Aedeagus of Schizohelea leucopeza (Meigen, 1804), extant male from Norway, coll. MAIG. G) Aedeagus of Monogedania clunipes (Loew, 1850), MAIG 3391. H) Dorsal aspect of male genitalia of Monogedania clunipes (Loew, 1850), redrawn from Szadziewski (1988).

Figure 4. Schizohelea baltica (Szadziewski, 1988), comb. nov., female MAIG 5624. A) Total habitus. B) Head. C) Distal tarsomeres and claws of hind legs.