Ardella Paulsen, 2021

Paulsen, M. J., 2021, Ardella magnaemirabilis (Coleoptera: Scarabaeidae: Melolonthinae: Ardellini), a new scarabaeoid species, genus and tribe from the southwestern United States, Insecta Mundi 2021 (903), pp. 1-5 : 2-3

Ardella Paulsen , new genus

Fig. 1–9

Type species. Ardella magnaemirabilis Paulsen , new species, here designated.

Description. Males. (females unknown). Color: Dorsum light reddish-brown, pronotum appearing lighter than elytra ( Fig. 1–2 ); abdomen varying from dark brown except pygidial disc lighter to entirely light brown. Head: Antenna of 9 antennomeres with 1 st –2 nd globose, 3 rd –5 th elongate and flat (3 rd as long as 4 th + 5 th), 6 th small, 7 th –9 th forming club of elongate lamellae; lamellae longer than antennomeres 1–6 together ( Fig. 5 ). Eyes large. Ocular canthus triangular, projecting, lower than frons and separated from it by supraocular carina. Frons raised medially, foveate each side near canthus. Clypeus concave, subcircular with base triangular ( Fig. 1, 5 ), surface sparsely and coarsely punctate. Clypeal suture evident, triangularly raised medially. Labrum not visible, apparently absent. Mandibles absent. Mentum narrow, flat ( Fig. 4 ). Thorax: Pronotum appearing strongly rounded in dorsal view, subangulate in lateral view, disc glabrous, convex (drying can cause irregular shrinking), punctate; punctures mixed fine and large. Pronotal margins finely beaded except membranous anterior margin. Lateral margin with long, sparse setae. Scutellum rounded, U-shaped. Elytra elongate, subparallel, surface with only sutural stria impressed in basal half, beginning behind scutellum; other striae suggested by rows of sparse, setose punctures; setae long, as long as distance between punctures ( Fig. 1 ). Sutural interval appearing raised in basal half where sutural stria is present. Metathoracic wings present ( Fig. 9 ). Metepisternum narrow, reaching metacoxa. Abdomen: Venter with 5 ventrites, sutures broadly membranous, more or less parallel and subequal in length (4 somewhat longer); ventrites and tergites including propygidium separated by wide membranous sutures; spiracles located in membranes. Pygidium triangular with rounded apex; position almost vertical. Surface smooth with fine punctures and long setae. Male genitalia with parameres contiguous, narrow, elongate and perpendicular to basal piece ( Fig. 6 ). Legs: Procoxae conical, contiguous. Protibia tridentate, lacking apical spur. Mesotibia and metatibia each with 1 transverse carina and paired, articulated apical spurs. Metatibial spurs arising well before metatibial apex so that spurs not reaching past apex in normal position ( Fig. 8 ), spurs arising subcontiguously, metatarsi not passing between (dorsal groove present to receive tarsi interior to spurs), one spur arising below tarsal insertion in lateral view (sensu Evans and Smith 2020). Metatarsomeres 1–4 with ventral carina that appears crenulate/fluted. Tarsal claws dissimilar, protarsal and mesotarsal claws toothed and cleft ( Fig. 7 ); metatarsal claws with indistinct tooth near base and appearing simple (not cleft).

Remarks. The new taxon and potential relatives were assessed for the following characters that were considered potentially informative: labrum absent, or if present, hidden or visible dorsally; claws simple or toothed; presence/ absence of ocular canthus; presence/absence of protibial spur; clypeal base elevated or not; club antennomeres elongate vs. short with oval club; ventrites 2 to 5 connate or separated; and the presence of fluting on metatarsomere 1 ( Table 1). This new genus does not share all characters with any other genus studied, and appears to differ in important ways that would preclude its membership in a known genus. It shares the most characters with species of Chasmatopterus Dejean from western Europe and northern Africa, but differs from those taxa in having an elongate antennal club and distinct (not connate) abdominal ventrites.

The most similar taxon with respect to the clypeus, antennal form, and claws is the South American tanyproctine genus Luispenaia Martínez ( Mondaca et al. 2019), however, species of that genus possess a distinct labrum, mandibles, and protibial spurs. In the key to tribes of Nearctic Melolonthinae in Evans and Smith (2020), Ardella will key to Phobetusini in couplet 9, however it differs significantly from Phobetus LeConte in lacking a labrum, protibial spur, and sternal spiracles. The proximal position of the metatibial spurs in Ardella such that they barely reach the metatibial apex appears to be unique among all taxa studied.

Etymology. Ardella , gender feminine, is dedicated to my late sister Ardell A. Paulsen .

Figures

Figures 1–9. Ardella magnaemirabilis Paulsen, new species. 1–4) Holotype male. 1) Dorsal view. 2) Lateral view. 3) Labels. 4) Ventral view of head and pronotum. 5–9) Paratype male. 5) Dorsal view of head and pronotum. 6) Oblique view of male genitalia.7) Cleft protarsal (left) and metatarsal (right) claws. 8) Dorsal view of right metatibia and metatarsus showing spurs not reaching past tibial apex and simple claws. 9) Right wing, dorsal view.