Amitus wellsae (Polaszek) Lahey & Talamas & Masner & Johnson, 2021

Lahey, Zachary, Talamas, Elijah, Masner, Lubomir & Johnson, Norman F., 2021, Revision of the Australian genus Alfredella Masner & Huggert (Hymenoptera, Platygastridae, Sceliotrachelinae), Journal of Hymenoptera Research 87, pp. 81-113 : 81

Amitus wellsae (Polaszek) comb. nov.

Figs 50-53 , 54-55 , 60

Masnerium wellsae Polaszek, 2009: 121 (original description).

Comments.

Polaszek (2009) established the genus Masnerium for a single male specimen reared from the whitefly Aleuroduplidens wellsae Martin ( Hemiptera , Aleyrodidae , Aleyrodinae ) in Australia ( Martin 1999). The following combination of characters was used to distinguish Masnerium from other sceliotrachelines: (1) submarginal vein of fore wing absent, (2) foamy structures on propodeum present, and (3) male antennae 8-merous ( Polaszek 2009). We posit that this character suite is not unique to Masnerium and that the taxon is best treated as a junior synonym of Amitus , a genus that was not discussed in Polaszek (2009). We base our appraisal on several character systems shared between Am. wellsae and other members of the genus, in addition to the morphology of the female, which we illustrate for the first time.

Character analysis.

(1) Submarginal vein of fore wing absent. This character is a hallmark of the genus Amitus , as it was used by Haldeman (1850) to derive the genus name. No Amitus species known to us have any remnant of tracheate fore wing venation. For this reason, this character is not useful for identifying Masnerium as a lineage separate from Amitus .

(2) Foamy structures on the propodeum. The presence of this character was given inflated importance by Polaszek (2009) because the taxa with which he compared Am. wellsae , Aleyroctonus and Aphanomerus , lack foamy structures entirely. The form and distribution of foamy structures in Am. wellsae is characteristic of other members Amitus and cannot be used to separate the two genera.

(3) Male antennae 8-merous. There is a tendency of the terminal antennomeres in certain playgastroid taxa to fuse, leaving no external trace (sutures) by which to determine the original number of segments (e.g., Pseudaphanomerus Szelényi). Similarly, in certain platygastroids the male antenna has converged in form with that of the female ( Talamas and Masner 2016) (e.g., Annettella gracilis Masner & Huggert; Aphanomerella Dodd; Errolium piceum Masner & Huggert; Helava Masner & Huggert; Microthoron Masner; Parabaeus Kieffer; Plutomerus Masner & Huggert; Psilanteris Kieffer; Tetrabaeus americanus (Brues)), making it difficult to distinguish between the sexes based on the antenna unless the papillary sensilla are visible or noticeable modifications have been made to the male sex-segment(s). The antenna of male Am. wellsae exhibits both types of modification: the apical antennomere (A8) lacks sutures, causing the shape of the antennal club to resemble that of the female due to the fusion of the terminal antennomeres (A8-A10). Because this has occured independently in numerous sceliotracheline genera, we do not consider it to indicate a separate genus. Rather, we refer to Masner and Huggert (1989) who put forth that this character is useful for diagnosing Australian species of Amitus .

(4) Number and arrangement of papillary sensilla. The number (4) and distribution (1-2-1) of papillary sensilla on the clava of Am. wellsae is characteristic of the genus.

(5) Epiclypeal carina . We coin this term to refer to the transverse carina located between the toruli and clypeus (Fig. 59 ). The epiclypeal carina is distinct from the epistomal sulcus because it terminates dorsal and lateral to the anterior tentorial pits. Amitus wellsae and all other species of the genus known to us possess this character, but the epiclypeal carina is not unique to Amitus . Neobia Masner & Huggert ( Sceliotrachelinae ) and some species of Leptacis Förster ( Platygastrinae ) also have this character.

(6) Structure of the dorsal mesosoma. The dorsal mesosoma is the most significant source of characters that separates Am. wellsae from its congeners. In Am. wellsae , the anterior margin of the mesoscutum is excavated between the antero-admedian lines, and the posteromedial margin of the mesoscutellum has a distinct rim. Other members of the genus either lack the excavated region on the anteromedial mesoscutum entirely or it is incomplete. Likewise, the posterior margin of the mesoscutellum lacks a defined rim in the non-Australian species of the genus. Most importantly, however, the transaxillar and axillular carinae are fused in Am. wellsae , a diagnostic character for Amitus (Figs 1 , 62 ).

(7) Structure of the lateral mesosoma. The morphology of the lateral mesosoma was not treated by Polaszek (2009) due to the mounting method. The structure of the lateral mesosoma in Am. wellsae is representative of the genus. The netrion is clearly indicated, the transepisternal line terminates in anterior and posterior pits, the acetabular carina is visible at the anteroventral edge of the mesopleuron, and the sculpture of the metapleural carina is foamy (Fig. 51 ).

Figures

Figure 1. Amitus granulosus MacGown & Nebeker, female holotype (USNMENT 01059097), head, mesosoma, metasoma, dorsal view. Scale bar in millimeters.

Figures 50 - 53. Amitus wellsae (Polaszek), female (OSUC 697974) 50 head, mesosoma, metasoma, dorsal view 51 head, mesosoma, metasoma, lateral view 52 mesosoma, posterodorsal view 53 head, anterior view. Scale bars in millimeters.

Figures 54 - 57. Amitus Haldeman antennal morphology 54 Amitus wellsae (Polaszek), female (NHMUK 010370369), lateral view 55 Amitus wellsae (Polaszek), male (NHMUK 010370506), lateral view 56 Amitus sp., female (OSUC 665643), lateral view (coated) 57 Amitus sp., male (USNMENT 00989622 _ 3), lateral view (coated). Scale bars in micrometers.

Figures 58 - 60. 58 Amitus sp., male (USNMENT 00989622 _ 2), mesosoma, ventral view (coated) 59 Amitus sp., male (USNMENT 00989622 _ 4), head, anterior view (coated) 60 Amitus wellsae (Polaszek), female (OSUC 697974), head and mesosoma, ventral view. Scale bars in millimeters.

Figures 62, 63. Comparative morphology of the scutellar-axillar complex in Amitus and Alfredella 62 Amitus sp., female (OSUC 665643), lateral view (coated) 63 Alfredella mephisto Lahey, male paratype (OSUC 697985), lateral view. Scale bars in micrometers.