Lepanus, Balthasar, 1966

Gunter, Nicole L. & Weir, Thomas A., 2019, Revision of Australian species of the dung beetle genus Lepanus (Coleoptera: Scarabaeidae: Scarabaeinae): key to species groups and description of 14 new species from the L. pygmaeus species group, Zootaxa 4564 (1), pp. 41-80 : 42-43

Key to species groups within Lepanus

The characters used in sexing Lepanus are more evident in some species groups than others. As a rule of thumb, the inner apical angle of the protibia of males extends into a digital process referred to as the apical digit (see examples in Figs 3H ; 4H, J ), correspondingly the apical spur is reduced. In females, the apical digit is either reduced or absent and the apical spur is larger (see examples in Fig 3G, I ). Furthermore, the length of abdominal ventrite 6 in males is usually shorter than that in females and there can be modifications to the shape of the metatibiae and metafemora in males.

1 Pygidium simple, rather flat or more-or-less convex ( Fig. 1 A–C)................................................ 2

- Pygidium with a depression, or large flat rugulose central area, with or without a transverse sinuate fold across the dorsal edge ( Fig. 1 D–F, 2A–F)..................................................................................... 4

2 Pygidial surface strongly sculptured with either prominent microreticulations or heavily punctate and/or setose, rather flat, basal margin strongly projecting ( Fig. 1A ); protibiae with 3 teeth on outer edge, inner apical edge truncate, apical spur present, and male apical digit short with small comb of short, stout setae at inner apex ( Fig. 3G ); elytra densely covered with obvious recurved setae (sometimes partly rubbed off)............................................. L. villosus species group

- Pygidial surface smooth, more-or-less convex, any punctures superficial, basal margin not strongly projecting ( Fig. 1 B–C); protibiae with 2 or 3 teeth on outer edge, inner apical edge angulate (always deeply angulate if 3 protibial teeth present), only rarely truncate, apical spur and male apical digit long either with or without a small comb of short, stout setae at the inner apex ( Fig. 3H ); elytra usually without obvious setae, if present, then recumbent only, not recurved.......................... 3

3 Protibiae with apical digit long in both males and females, with a small comb of short, stout setae at right angle to digit in males or in same plane in females; apical spur present on outer apical edge in both males and females; protibiae usually with 3 teeth on outer edge, rarely with 2 teeth (e.g., L. monteithi ); inner apical edge of protibiae deeply angulate; hypomeral striae absent; basal margin of pronotum evenly rounded........................................ L. monteithi species group

- Protibiae with apical digit long in males and shorter in females, without a small comb of setae; apical spur present only in females, located apically; protibiae with 2 teeth on outer edge; inner apical edge of protibiae less angulate or rarely truncate; hypomeral striae usually present; basal margin of pronotum usually slightly angulate in the middle. L. australis species group

4 Pygidium with a transverse sinuate fold, mostly in upper part and appearing as a duplication of basal margin; pygidium with or without a depression ( Fig. 1 D–F)......................................................................... 5

- Pygidium without a transverse sinuate fold; pygidium always with a depression of various sorts or otherwise modified central area ( Fig. 2 A–F)...................................................................................... 6

5 Pygidium with a large, shallow depressed central area that is reticulate and usually contrastingly matt, upper edge of depression gently concave ( Fig. 1D ); protibiae with 2 or 3 teeth on outer edge, inner apical edge truncate; hypomeral striae absent; edge of head entirely bordered, dorsal part of eye moderate to wide in size; relatively large in length 3.5–6.5 mm ........................................................................................... L. ustulatus species group

- Pygidium either without a depression ( Fig. 1E ), or with a deeper, rather ovoid depression that is reticulate and contrastingly matt, and extends under the sharp, more concave upper edge (this depression has a continuous sharp edge in female L. storeyi ) ( Fig. 1F ); protibiae with 2 teeth on outer edge, inner apical edge deeply angulate; hypomeral striae present; edge of head bordered only between the eye canthus and the angulation of the clypeogenal suture, dorsal part of eye narrow in size; generally small in length 2.4–3.2 mm ............................................................ L. storeyi species group

6 Pygidium with a large flat central area that is reticulate and contrastingly matt ( Fig. 2A ); protibiae of male with short, broad apical digit and blade-like apical spur; male mesotibiae expanded towards the apex, with a small brush of setae along the expansion; hypomeral striae absent; elytral striae 8 obvious and curving inwards apically; size usually larger, length 3.5–5.2 mm ............................................................................... L. nitidus species group

- Pygidium with a depression of various sorts ( Fig. 2 B–F); protibiae of male with apical digit variously shaped but not as above, and apical spur present or absent; hypomeral striae usually present; elytral striae 8 usually not as obvious, less curving inwards apically; size usually smaller, length 1.8–3.8 mm ............................................................. 7

7 Pygidial depression without a well-defined lower lip, merging gradually with discal surface below and extending under basal margin ( Fig. 2B ); elytral striae obsolete................................................. L. pisoniae species group

- Pygidial depression variously shaped, with a defined lower lip ( Fig. 2 C–F), EITHER somewhat transverse with only upper and lower lips well defined and usually sharp ( Fig. 2 C–D) OR with rounded edges ( Fig. 2F ) OR with continuous sharp margins, sometimes with a median tubercle ( Fig. 2E ); elytral striae usually visible, although may only be lightly impressed......... 8

8 Pygidial depression somewhat transverse, with only upper and lower lips well defined and usually sharp, with or without a pit in the upper angle of pygidial depression ( Fig. 2 C–D); inner apical edge of protibiae deeply angulate; male apical digit long and slender, as long as apical protibial tooth, apical spur absent................................................. 9

- Pygidial depression without a defined lower lip as above, but either with defined continuous sharp edges, or without any sharp edges, sometimes with a median tubercle ( Fig. 2 E–F); inner apical edge of protibiae deeply angulate or truncate; male apical digit somewhat shorter and broader, usually shorter than apical protibial tooth, apical spur present or absent............. 10

9 Pygidial depression with a concave upper lip and straight lower lip, with a pit in the upper angle of pygidial depression ( Fig. 2C ); head with obvious fine, recumbent setae............................................ L. furcifer species group

- Pygidial depression with upper and lower lips of various shapes, without a pit in the upper angle Fig. 2D ); head lacking setae.............................................................................. L. parapisoniae species group

10 Pygidial depression with defined, continuous sharp edges, usually with a small tubercle within depression ( Fig. 2E ); basal margin of pronotum usually rounded.................................................... L. pygmaeus species group

- Pygidial depression without defined sharp edges, never with a tubercle within the depression ( Fig. 2F ); basal margin of pronotum usually slightly angulate....................................................... L. palumensis species group

Figures

FIGURE 1. Examples of general configuration of pygidia in Lepanus species groups represented by species for which species group name is derived. A, Lepanus villosus; B, L. monteithi; C, L. australis; D, L. ustulatus; E, L. storeyi (♂); F, L. storeyi (♀). Note, within the L. storeyi species group only Lepanus storeyi is sexually dimorphic, the pygidia of all other females are similar to L. storeyi males, this is also the only Lepanus species that exhibits such dimorphic pygidia.

FIGURE 2. Examples of general configuration of pygidia in Lepanus species groups represented by species for which species group name is derived. A, Lepanus nitidus; B, L. pisoniae; C, L. furcifer (arrow showing position of pit); D, L. parapisoniae; E, L. pygmaeus; F, L. palumensis.

FIGURE 3. A, Dorsal aspect of key structures of Lepanus and other dung beetles; B, Ventral aspect of key structures of Lepanus and other dung beetles; C, key structures of a Lepanus head; D–F, aspect of the eye canthus relative to the eye: D, dividing the eye; E, nearly dividing the eye (separated by only a few eye facets); F, not dividing the eye; G–H, examples and key structures of Lepanus protibia: G, dorsal aspect of truncate protibia; H, dorsal aspect of deeply angulate protibia.

FIGURE 4. Some diagnostic characters of the Lepanus pygmaeus species group. A, Head of Lepanus guthrieae featuring medially interrupted basal margin (white arrow) and reticulations on clypeal area only (black arrow); B, head of Lepanus lentil featuring angulate and complete basal margin (white arrow); C, pterothorax of Lepanus andersonorum showing fine, short carina extending backwards from the meso-metaventral suture (white arrow); D, posterior aspect of metatibia of Lepanus pecki; E, anterior aspect of metatibia of Lepanus pecki; F, anterior aspect of metatibia of Lepanus guthrieae; G, female protibia of Lepanus pygmaeus; H, male protibia of Lepanus pygmaeus; I, female protibia of Lepanus pecki; J, male protibia of Lepanus pecki; K, male protibia of Lepanus crenidens; L, male protibia of Lepanus pungalina; M, inner laterodorsal aspect male protibia of Lepanus pungalina showing bent apical digit (black arrow).