Lepanus pygmaeus (Macleay, 1888)

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 : 49-50

Key to species Lepanus pygmaeus species group

Due to the subtle nature of some diagnostic characters, some specimens are difficult to diagnose. Images of some diagnostic characters are provided in Figs. 4–12 to help facilitate diagnoses. Given the small size of specimens (1.8–3.0 mm), a high-powered microscope with adequate lighting is recommended for identification. Furthermore, caution must be taken when interpreting setation on specimens as fine setae rub off and may appear absent.

1 Protibia with three teeth on outer edge, basal tooth sometimes very small ( Fig. 4 I–J)................................ 2

- Protibia with two teeth on outer edge ( Fig. 4 G–H, K–L)....................................................... 3

2 Pygidium with a tear-drop shaped depression extending under the usually straight upper edge, depression with an elongate tubercle ( Fig. 9E ); male metatibiae with almost straight inner edge; female 6 th abdominal ventrite swollen in middle; aedeagus ( Fig.12D )......................................................... Lepanus sauroni Gunter & Weir , new species

- Pygidium with an almost ovoid depression just extending under the usually angulate upper edge, depression with a round tubercle ( Fig. 9A ); male metatibiae with expanded inner edge, creating a distinct flange ( Fig. 4 D–E); female 6 th abdominal ventrite not swollen; aedeagus as in Fig. 11E .............................. Lepanus pecki Gunter & Weir , new species

3 Front edge of protibia truncate ( Figs. 3G , 4 G–H); apical digit absent in females ( Fig. 4G )............................. 4

- Front edge of protibia deeply angulate ( Fig. 3H ); apical digit present in females (as in Fig. 4I )......................... 5

4 Pygidial depression widely pear shaped with a somewhat triangular tubercle in the upper third, upper edge of pygidium narrowly angulate, depression just extending under the edge ( Fig. 9D ); punctures along basal margin of prothorax slightly elongate, differing from those on the disc; dorsal part of the eye moderate in size; aedeagus ( Fig. 12C ).............................................................................................. Lepanus pygmaeus ( Macleay, 1888)

- Pygidial depression round with a round tubercle in the upper third, upper edge of pygidium broadly angulate, depression extending under the edge ( Fig. 9F ); punctures along basal margin of prothorax more round, similar to those on the disc; dorsal part of the eye narrower in size; aedeagus ( Fig. 12E )..................... Lepanus tozerensis Gunter & Weir , new species

5 Pygidial depression narrow and vertically elongate, without a tubercle, occupying less than half the area of the pygidial disc ( Fig. 8F ), basal carina of head complete, with a slight medial angle ( Fig. 4B ); aedeagus as in Fig. 11A ..................................................................................... Lepanus lentil Gunter & Weir , new species

- Pygidial depression of different shape, usually occupying at least one third to half the area of the pygidial disc (smaller and round in L. menendezae ), depression with or without a distinct tubercle; basal carina of head either obsolete, or interrupted medially............................................................................................. 6 6 Pygidial depression a narrow or broad U-shape, without a distinct tubercle ( Figs. 8A, G ); basal carina of head absent or obsolete; basal margin of pronotum slightly angulate medially...................................................... 7

- Pygidial depression different, either round (e.g., Figs. 8C, I ), ovoid (e.g., Fig. 8H ), pear or tear-drop shaped (e.g., Figs. 8D , 9 B–C), with a distinct tubercle; basal carina of head present, medially interrupted ( Fig. 4A ); basal margin of pronotum rounded medially............................................................................................. 8

7 Pygidial depression narrow U-shape, reticulate, occupying the medial third of the pygidial disc ( Fig. 8A ); surface of the head finely reticulate between clypeogenal suture and anterior edge, rest of head smooth (as in Fig. 4A ); dorsal part of eye moderate, interocular space about 10 times the width of dorsal part of the eye; with a fine carina extending backwards from the mesometaventral suture ( Fig. 4C ); elytral surface reticulate in apical half and at the sides, striae slightly impressed, striae 5–7 similar to striae 1–4; aedeagus as in Fig. 10A .......................... Lepanus andersonorum Gunter & Weir , new species

- Pygidial depression broad U-shape, smooth, occupying at least medial half of the pygidial disc ( Fig. 8G ); surface of head entirely smooth; dorsal part of eye narrow in size, interocular space about 16 times the width of dorsal part of the eye; without a fine carina extending backwards from the meso-metaventral suture; elytral surface smooth, striae superficial, striae 5–7 weaker than striae 1–4; aedeagus as in Fig. 11B .......................... Lepanus lingziae Gunter & Weir , new species

8 Pygidial depression pear or tear-drop shaped ( Figs. 8D , 9 B–C).................................................. 9

- Pygidial depression round or ovoid ( Figs. 8 B–C, E, H–I)..................................................... 11

9 Pygidium with an evident secondary basal line across base of depression, pygidial depression tear-drop shaped, not reaching base, tubercle slightly elongate ( Fig. 9C ); mesoventrite with discernible punctures at least at sides; surface of the head finely reticulate between clypeogenal suture and anterior edge (as in Fig. 4A ); aedeagus as in Fig. 12B ...................................................................................... Lepanus pungalina Gunter & Weir , new species

- Pygidium with secondary basal line not evident, merged with base, pygidial depression reaching base, tubercle elongate or an inverted V ( Figs. 8D , 9B ); mesoventrite with or without discernible punctures; surface of head entirely smooth.......... 10

10 Pygidial depression widely pear shaped, tubercle elongate ( Fig. 9B ); elytral flange and groove relatively wide; colour dark brown to black with red humeri ( Fig. 6E ); mesoventrite with discernible punctures at least at sides; aedeagus as in Fig. 12A ................................................................. Lepanus podocarp Gunter & Weir , new species

- Pygidial depression narrowly tear-drop shaped, tubercle an inverted V ( Fig. 8D ); elytral flange and groove narrower; colour uniformly dark brown ( Fig. 5D ); mesoventrite virtually impunctate; aedeagus as in Fig. 10D ............................................................................................ Lepanus gubara Gunter & Weir , new species

11 Pygidial depression small and round, occupying less than half of the pygidial disc, separated from base, tubercle round and centrally located; secondary basal line evident ( Fig. 8I ); aedeagus as in Fig. 11D ................................................................................................. Lepanus menendezae Gunter & Weir , new species

- Pygidial depression larger, occupying about half of the pygidial disc, usually reaching the base ( Figs. 8 B–C, E, H); secondary basal line evident or not............................................................................... 12

12 Pygidium with evident secondary basal line across base of depression, depression usually not reaching base, tubercle tubular with a dark tip ( Fig. 8E ); mesoventrite with discernible punctures at least at sides and often reticulate; surface of the head finely reticulate between clypeogenal suture and anterior edge; elytral striae 6 and 7 appearing double, similar to striae 1–5; male metatibia with expanded inner edge, creating a small flange ( Fig. 4F ); aedeagus as in Fig. 10E .................................................................................... Lepanus guthrieae Gunter & Weir , new species

- Pygidium with secondary basal line not evident, merged with base, upper edge of depression angulate, tubercle of various shapes ( Figs. 8 B–C, H); mesoventrite virtually impunctate, not reticulate; surface of head usually entirely smooth; elytral striae 6 and 7 appearing single, different from striae 1–4 or 1–5; male metatibia with inner edge not expanded............... 13

13 Apical tooth on protibiae with a slight notch on the inner edge ( Fig. 4K ) [often best viewed from below]; tubercle within pygidial depression low, round, or slightly elongate, same colour as depression ( Fig. 8B ); eye canthus not dividing the eye (as in Fig. 3F ); aedeagus as in Fig. 10B .................................. Lepanus crenidens Gunter & Weir , new species

- Apical tooth on protibiae without a notch on the inner edge; tubercle within pygidial depression with a darker tip, either shaped as an inverted V or slightly horizontal; eye canthus nearly dividing the eye (as in Fig. 3E )........................... 14

14 Pygidial depression with tubercle somewhat inverted V shaped ( Fig. 8C ); elytral striae 5–7 with discernible punctures at least in basal half; elytral flange and groove relatively wide; basal margin of pronotum with a distinct row of punctures ( Fig. 5C ); aedeagus as in Fig. 10C .............................................. Lepanus feehani Gunter & Weir , new species

- Pygidial depression with tubercle slightly horizontal, not like an inverted V ( Fig. 8H ); elytral striae 5–7 without discernible punctures; elytral flange and groove narrower; basal margin of pronotum without a distinct row of punctures ( Fig. 6B ); aedeagus as in Fig. 11C ................................................ Lepanus mckenziei Gunter & Weir , new species

Figures

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).

FIGURE 5. Habitus of species within the Lepanus pygmaeus species group. A, Lepanus andersonorum; B, Lepanus crenidens; C, Lepanus feehani; D, Lepanus gubara; E, Lepanus guthrieae; F, Lepanus lentil. All specimens in comparative scale. Scale bar 1 mm.

FIGURE 6. Habitus of species within the Lepanus pygmaeus species group. A, Lepanus lingziae; B, Lepanus mckenziei; C, Lepanus menendezae; D, Lepanus pecki; E: Lepanus podocarp; F, Lepanus pungalina. All specimens in comparative scale. Scale bar 1 mm.

FIGURE 7. Habitus of species within the Lepanus pygmaeus species group. A, Lepanus pygmaeus; B, Lepanus sauroni; C, Lepanus tozerensis. All specimens in comparative scale. Scale bar 1 mm.

FIGURE 8. Pygidial configuration of species within the Lepanus pygmaeus species group. A, Lepanus andersonorum; B, Lepanus crenidens; C, Lepanus feehani; D, Lepanus gubara; E, Lepanus guthrieae; F, Lepanus lentil; G, Lepanus lingziae; H, Lepanus mckenziei; I, Lepanus menendezae. All specimens in comparative scale. Scale bar 0.2 mm.

FIGURE 9. Pygidial configuration of species within the Lepanus pygmaeus species group. A, Lepanus pecki; B, Lepanus podocarp; C: Lepanus pungalina; D, Lepanus pygmaeus; E, Lepanus sauroni; F, Lepanus tozerensis. All specimens in comparative scale. Scale bar 0.2 mm.

FIGURE 10. Left, dorsal, and right view of aedeagi of species within the Lepanus pygmaeus species group. A, Lepanus andersonorum; B, Lepanus crenidens; C, Lepanus feehani; D, Lepanus gubara; E, Lepanus guthrieae. Not in comparative scale, given size difference aedegi are roughly grouped in three size classes as per lower left schematic and scaled accordingly. Size class indicated by shaded silhouette and 0.2 mm scale bar.

FIGURE 11. Left, dorsal, and right view of aedeagi of species within the Lepanus pygmaeus species group. A, Lepanus lentil; B, Lepanus lingziae; C, Lepanus mckenziei; D, Lepanus menendezae; E, Lepanus pecki. Not in comparative scale, given size difference aedegi are roughly grouped in three size classes as per lower left schematic and scaled accordingly. Size class indicated by shaded silhouette and 0.2 mm scale bar.

FIGURE 12. Left, dorsal, and right view of aedeagi of species within the Lepanus pygmaeus species group. A, Lepanus podocarp; B, Lepanus pungalina; C, Lepanus pygmaeus; D, Lepanus sauroni; E: Lepanus tozerensis. Not in comparative scale, given size difference aedegi are roughly grouped in three size classes as per lower left schematic and scaled accordingly. Size class indicated by shaded silhouette and 0.2 mm scale bar.