Scirtidae, Fleming, 1821

Watts, C. H. S., Bradford, T. M. & Cooper, S. J. B., 2021, A new genus, Perplexacara, and new generic placements of species of Australian marsh beetles (Coleoptera: Scirtidae) based on morphology and molecular genetic data, Zootaxa 4927 (4), pp. 539-548 : 545-546

Key to the genera and species of Australian Scirtidae with either or both an enlarged scape and very small antennomeres 2 & 3 or a well-marked subantennal groove: genera included in this paper plus Calvarium Pic, Pachycyphon Zwick, Prionocyphon and Spaniosdascillus Watts. (Based on key in Watts & Zwick (2019)).

1 Supraantennal ridge strong, long, turning ventrally in front of eye and forming a distinct groove and ridge forwards from the eye. Antennomere 2 not much shorter than scape........................................................... 2

- Supraantennal ridge short, ending where it meets the edge of the eye; no crest or deep groove in front of eye. Antennomere 2 much smaller than scape............................................................................... 6

2(1) Ventrites 1–4 connate. Restricted to higher regions of north Queensland ( Zwick 2014)............... Pachycyphon Zwick

- Ventrites not connate. Found in wetter areas from Northern Australia to Tasmania ................................. 3

3(2) Scape large, disc-shaped with sharp anterior edge ( Zwick 2014)..................................... Calvarium Pic

- Scape of normal size, not as above........................................................................ 4

4(3) Mandibles strongly projecting. Anterolateral angles of pronotum projecting forward. Mesepisternum rugose. Gonocoxites elongate, gonostyli small to medium in length.................................................................. 5

- Mandibles not strongly projecting. Anterolateral angles of pronotum rounded. Mesepisternum smooth. Gonocoxites widely triangular, shovel-like, gonostyli minute ( Watts 2011)............................. Chameloscyphon huonensis Watts

5 (4) Length 3.0– 4.5mm. Elytral punctures much larger than those on pronotum. Mesoventral process longer than wide. Female winged, ventrite 4 without transverse row of setae............................................ Dasyscyphon Watts

- Length 7–11mm. Elytral punctures similar to those on pronotum or smaller. Mesoventral process longer than wide. Female micropterous, ventrite 4 with transverse row of setae............................................ Daploeuros Watts

6(1) Length 3.0– 5.4mm. Mandible with one small tooth; mesoventral notch weakly developed, obsolete or shallowly U-shaped..................................................................................................... 7

- Length 4.5–11.0mm. Mandible with several strong teeth; mesoventral notch well developed, deep, V-shaped........... 9

7(6) Mandibles very broad, as wide as long, tips short; eyes small, base of eye width of 8–10 eye facets from subgenal ridge; Tasmania ..................................................................... P. latusmandibulara (Watts)

- Mandibles much longer than wide, tips long; eyes medium to large, base of eye width 1–4 eye facets from subgenal ridge; mainland of Australia and Tasmania ...................................................................... 8

8(6) Length 3.8–5.4mm. Distance from edge of eye to subgenal ridge width of 1–2 eye facets.......... P. macroflavida (Watts)

- Length 3.0– 3.4mm. Distance from bottom of eye to subgenal ridge width of 3–4 eye facets.......... P. caementum (Watts)

9 (7) Labial palpi straight; elytra with ribs or uneven surface...................................................... 10

- Labial palpi forked; elytra without ribs, surface smooth...................................................... 11

10(9) Apical segments of maxillary and labial palpi with obliquely truncated apexes ( Watts 2011); often with uneven dorsal surface.................................................................................... M. pannuceus Watts - Apical segments of maxillary and labial palpi with rounded apexes; male with smooth dorsal surface...... M. scalaris (Lea)

11(9) Elongate, penultimate segment of labial palpus broad, scoop-like.............................. Spaniosdascillus Watts

- Oval, penultimate segment of labial palpus elongate-oval, not scoop-like........................................ 12

12(11) Subgenal ridge with buttonhole (sensu Zwick 2016); pilosity on first ventrite heterogeneous.......... Prionocyphon species

- Subgenal ridge without buttonhole; pilosity on first ventrite homogeneous except for small area in M. insolitus .................................................................................................. 13

13 (12) Head not depressed between eyes; pronotum strongly punctate, punctures much larger than setae bases; Tasmania ............................................................................................. M. insolitus (Watts)

- Head depressed between eyes; pronotum with punctures little larger than setae bases; coastal New South Wales and southern Queensland .................................................................... M. lamingtonensis (Watts)