Macrodascillus Carter, 1935

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 : 542-543

Macrodascillus Carter, 1935 ( Figs 2–4 )

Modified description. Length 4.5–11.0mm. Eye normal size; without well-marked subantennal carina, without subantennal groove; antenna with scape greatly enlarged, widely oval, compressed, upper edge sharp, antennomere 2 small, inserted at end of scape, antennomere 3 smaller, together equal to or shorter than antennomere 4; subgenal ridge without buttonhole; with one strong mandibular tooth and a smaller one and/or a roughened area behind it; labial palpi forked (sensu Watts & Zwick 2019) or straight; anterolateral angles of pronotum square or projected forward, anterolateral angles of clypeus not projecting forward; mesoventral notch relatively long, narrowly ‘V’- shaped; pilosity on ventrites uniform except in M. insolitus which has a small area of larger punctures/setae on each side of ventrite. Male genitalia relatively simple, without endophallus (Fig. 66 in Watts 2011). Females winged, gonocoxites elongate, never strongly sclerotized.

Notes. Macrodascillus was first proposed by Carter (1935) to accommodate a large scirtid from Barrington Tops New South Wales which he named M. denticornis . This species was subsequently shown by Watts (2011) to be conspecific with Helodes scalaris Lea, 1895 leading to the placement of H. scalaris into Macrodascillus . The species is recognized by its large size, enlarged scape, very small antennomeres 2 and 3, serrated antennae particularly in the male, strong mandibles each with a tooth, the anterolateral angles of the pronotum projected forward, male genitalia simple and female ovipositor simple with well-developed prehensor ( Watts 2011, Watts & Zwick 2019). A second relatively similar species, M. pannuceus Watts , was added by Watts (2011). This paper adds two additional species, M. insolitus ( Watts 2010) and M. lamingtonensis ( Watts 2010) . When describing these two species Watts 2010 drew attention to their similarity to M. scalaris , particularly the form of the scape and antennomeres 2 and 3. Phylogenetic analysis of the sequence data in this paper places both of these species as congeneric with M. scalaris and we herein transfer them from Prionocyphon Redenbacher to Macrodascillus Carter.

The larvae of three of the species now in Macrodascillus are known ( Watts 2014). Those of M. insolitus and M. scalaris are saproxylic and those of M. lamingtonensis live in small rock pools beside creeks and rivers. These larvae are morphologically distinct from each other and do not support a close relationship between these three species.

The genus as now constituted is found in wet Eucalypt forest from southern Queensland to southern Tasmania with one species ( M. pannuceus ) restricted to higher areas of the Atherton Tablelands .

Included species. Macrodascillus insolitus ( Watts, 2010) , M. lamingtonensis ( Watts, 2010) , M. scalaris ( Lea, 1895) , M. pannuceus Watts, 2011 .

Figures

FIGURES 2–7. Habitus: 2–4, Macrodascillus species, 5–7, Perplexacara species. 2, Macrodascillus lamingtonensis (Watts); 3, M. insolitus (Watts); 4, M. scalaris (Lea); 5, Perplexacara latusmandibulara (Watts); 6, P. caementum (Watts); 7, P. macroflavida (Watts).