Xeropsalta aridula, Ewart, 2018

Ewart, A., 2018, Two new genera and five new species of Mugadina - like small grass cicadas (Hemiptera: Cicadidae: Cicadettini) from Central and Eastern Australia: comparative morphology, songs, behaviour and distributions, Zootaxa 4413 (1), pp. 1-56 : 34-39

Xeropsalta aridula n. sp.

Fig. 2D – 7D , 8 , 22–24 , 30 , Pl. 5, 6A.

Urabunana species A (Cravens Grass Chirper; no. 634), Ewart 2009: 121, 127 (Pl. 2, K, L), 128, 144.

Types. QUEENSLAND. Holotype male, T 244501, 100m W. Cravens Pk Hstd., via Boulia, SWQ, Button grassland, 10.ii.2007, A.E., 23°19.38'S 138°35.36'E (QM).

Paratypes. QUEENSLAND. 19♂, 5♀, 100m W. Cravens Pk Hstd., via Boulia, SWQ, Button grassland, 10.ii.2007, A.E., 23°19.38'S 138°35.36'E (AE) . 1♀, location as previously, 21.ii.2007, A.E. (QM). 2♂, Mulligan R. alluvial plain, jct. of fences of Carlo, Cravens Peak, Glenormiston Properties, grassland, 12.ii.2007, A.E., 23°23.28'S 138°39.97'E; 1♂; 2.3 km N. Cravens Peak Hstd, via Boulia, SEQ, grassland, 13.ii.2007, A.E., 23°18.28'S 138°34.69'E (AE). 1♂, 1♀, 100m W. Cravens Pk Hstd., via Boulia, SWQ, Button grassland, 10.ii.2007, A.E., 23°19.38'S 138°35.36'E (ANIC). 1♂, 100m W. Cravens Pk Hstd., via Boulia, SWQ, Button grassland, 10.ii.2007, A.E., 23°19.38'S 138°35.36'E (BMNH). 1♂, 1♀, 100m W. Cravens Pk Hstd., via Boulia, SWQ, Button grassland, 10.ii.2007, A.E., 23°19.38'S 138°35.36'E (MSM).

Distribution ( Fig. 8 ). Known from the Cravens Peak Hstd., and adjacent properties, located within the eastern Simpson Desert, far S.W. Queensland.

Habitat. Open grassland in desert environment, dry for long periods, but with relatively short term recovery after rains. The grasses include abundant Button Grass Dactyloctenium radulans , common in disturbed areas. Specimens captured in February after abnormally heavy rains.

Description. MALE (Pl. 5A, B). Head: Supra-antennal plate dull black, anteriorly tending deep brown; postclypeus pale yellowish-brown around anterior margins, also in medial suture between transverse ridges; transverse ridges black, this partially extending on to dorsal surface anterior-laterally; minor extension of pale yellow-brown colour between ridges; posterior areas of dorsal surface pale yellow-brown; gena pale yellowishbrown with sparse yellow pubescence; mandibular plate black centrally, otherwise pale yellow-brown; frons black with a yellow central fascia extending to, and continuing distally from anterior ocellus; vertex black which surrounds lateral ocelli, with irregular pale yellow-brown laterally, extending to anterior margin of pronotum; epicranial suture pale yellow-brown; ocelli pale reddish hue; compound eyes dark brown; anteclypeus dark brown laterally, pale yellow brown distally and anteriorly; mentum pale yellow; rostrum dark brown; pedicels brown, antennae deep brown.

Thorax: Pronotum with central fascia dark brown, enclosed by a broad dark brown to black envelope which partially splays out anteriorly adjacent to anterior pronotal margin, and distally along margin of pronotal collar; remainder of pronotum mainly pale yellowish-brown, but with broken and irregular black to deep brown markings in and between the paramedian and lateral fissures; anterior pronotal margin pale brown, pronotal collar medium brown, darker on lateral angles. Mesonotum with dull black submedian and lateral sigilla, the latter with broken and irregular margins; extending distally from (and between) the submedian sigilla is a medium to dark brown broad fascia which widens towards the cruciform elevation, completely filling the area between the two anterior arms of the cruciform elevation, including the scutal depression; areas between the sigilla are pale yellow; laterally from the lateral sigilla coloured pale brown and yellowish-brown; cruciform elevation yellowish-brown, brown centrally; area between the lateral cruciform arms pale yellow; wing grooves pale brown to yellow-brown, with short sparse yellow pubescence. Metanotum pale yellow-brown, narrow brown area on dorsal mid-line.

Wings: Forewing. Pterostigma off-white, slightly translucent; costal vein pale brown, slightly darker brown along anterior margin; remaining venation pale to medium brown, darker towards wing margins; basal membrane white to off-white. Hind wing venation pale to medium brown colouration; plaga and area adjacent to 3A and 2A veins opaque white, very faintly brown centrally along the plaga; no infuscations.

Legs: Fore coxae dark brown on anterior faces, otherwise pale yellow-brown; mid and hind coxae with broken pale brown areas with diffuse darker brown fasciae; trochanters predominantly pale to medium brown; femora predominantly pale brown with medium brown fasciae; dark brown spines on fore femora; tibiae and tarsi pale to medium brown, tips of claws deep brown.

Opercula: Uniformly pale yellow except crest which is medium to dark brown; markedly domed and on basal area, broad ridge on lateral area; in outline, rounded but markedly elongated along axis from crest to distal-medial area.

Timbals: Long ribs moderately sclerotised rib structures, these as in diagnosis with rib 4 clearly fused dorsally to basal spur; timbal plate broadly domed.

Abdomen: Tergite 1 medium to dark brown, pale yellow-brown along dorsal midline; tergite 2 medium-brown along dorsal and sub-dorsal areas, becoming mainly pale yellow ventro-laterally, the boundaries between the colour segments diffuse; auditory capsule pale to medium brown, darker along margins; tergites 3 to 7 again brown along dorsal and sub-dorsal areas, tending slightly darker dorsally, laterally irregularly grading to pale yellowbrown; ventro-laterally distinctly darker brown within which are prominent roughly triangular black patches with diffuse outlines; in some specimens, the brown dorsal colouration is more extensive (Pl. 5B); along the actual ventro-lateral margins the colour again changes to yellowish-brown to darker brown; tergite 8 predominantly medium to darker brown, the colouration markedly variable across the tergite; tergite 8 predominantly medium to darker brown, the colours markedly variable across the tergite; the above described colours do not extend across intersegmental membranes which are consistently pale yellow-brown. Pygofer dominantly pale yellow-brown distally, changing to deep brown along and adjacent to anterior margin. Sternite II medially deep brown, laterally pale yellow-brown; sternites III to V medium brown medially, the colour not extending to and across intersegmental membranes, the remaining colouration pale yellowish-brown; intersegmental membranes are pale yellowish-brown; sternite VI mostly medium brown, darker distally; sternite VIII with two almost coalesced anterior black to deep brown areas, the dominant area of sternite medium to pale yellow-brown, the detailed distribution of the colours somewhat patchy. Essential genital structures as in diagnosis.

FEMALE (Pl. 6A). Note that the pristine colour of the females of this species is a pristine pale green, this colour, however, degrading to yellow in set and dried specimens, with small scattered green remnant spots. The colour and markings (or lack thereof) of the females are completely different from those of the males; this colouration, combined with reduced tendency for flight, ensures that the females remain very cryptic in the grass habitat.

Head. Supra-antennal plate, vertex, frons, postclypeus (including transverse ridges), gena, mandibular plates, pedicels, and anteclypeus are all uniformly pale to medium yellow, with small irregular remnant green patches, especially along and within the margins of the different morphological units and the folds within these; ocelli pale pink to colourless; compound eyes medium brown; labrum, mentum yellow, labium very pale yellow, becoming partially brown apically; rostrum extends to mid-coxae.

Thorax. Pronotum and pronotal collar yellow with small remnant green spots within the paramedian and lateral fissures, also along anterior margin. Mesonotum yellow, including the sigilla, the outlines of the submedian sigilla are just discernible, the outlines of the lateral sigilla are obscure; cruciform elevation and wing grooves are yellow. Metanotum yellow.

Wings. Venation very pale yellow to off-white; basal membrane off-white to white.

Legs. Uniformly yellow with small remnant pale green patches, most visible on coxae; tarsi tending pale brown, claws dark brown.

Abdomen. Tergites all pale yellow with remnant green along intersegmental membranes and ventral posterior margins of some tergites; tergite 9 entirely yellow; ovipositor sheath pale brown; sternites yellow with remnant green patches. Ovipositor sheath extends 1.6 to 1.7 mm beyond termination of final sternite.

Measurements. N= 13♂ 8♀. Ranges and means (in parentheses), mm; BL: ♂ 11.3–13.8 (12.9); ♀ 10.8–12.5 (12.0). FWL: ♂ 11.4–13.3 (12.1); ♀ 10.7–12.0 (11.4). HW: ♂ 2.7–3.1 (2.9); ♀ 2.7–2.9 (2.8). PW: ♂ 2.6–3.0 (2.9); ♀ 2.7–2.9 (2.8). AW: ♂ 3.9–4.5 (4.3); ♀ 3.2–3.8 (3.5). FWL/WR: ♂ 2.47–2.96 (2.64); ♀ 2.51–2.73 (2.61). Etymology: Latin term referring to a desert environment, specifically the eastern Simpson Desert in which this species was discovered.

Figures

FIGURE 8. Map of Central and Northeastern Australia, showing the currently known occurrences of Heremusina udeoecetes n. sp., H. pipatio n. sp., Xeropsalta thomsoni n. sp., X.aridula n. sp., and X. rattrayi n. sp. The heavy dot-dash line shows the approximate northern and eastern boundaries of the ecoregion which defines the dominance of deserts and xeric shrublands within inland Australia (based on National Reserve System map, published by the Australian Government). The fine dotted lines are major roads, the names of some prominent towns listed. Lake Eyre and associated ephemoral lakes are shown by the darker shading. The approximate outlines of the modern dunefields comprising much of the Simpson and Strzelecki deserts are shown by the lighter shading, these based on 'Google Earth' images.

FIGURE 22. Xeropsalta aridula n. sp., field recordings (with parabola), Cravens Peak area, eastern Simpson Desert, far western Queensland, low grassland (following heavy rains), mostly disturbed vegetation, locally dominated by introduced buttongrass (Dactyloctenium radulans). (A) waveformoverview of acomplete phrase showing therepetitive discreteechemes, these ranging between 236–375 ms in duration, with RR of 2.6 Hz. The initial echemes are longer than the following echemes. (B) Another waveform plot showing echemes which are fragmented into shorter phrases, each comprised varying numbers of echemes, commonly observed in theX.aridula n. sp. songs.(C)time expanded waveform of initial echeme shown in Fig.22B, illustrating the increasing pulse amplitudes, reaching a maximum at ~400 ms, followed by a slight amplitude decline, the termination marked by a sharp break, followed by a discrete macrosyllable. Fig. 22D, E, further time expanded waveform and envelopecurve of the endof an echeme (excluding the final discrete macrosyllable),showing the detailed pulse structures,with the development of well defined macrosyllables, each comprising 6 primary pulses, each immediately followed by (in fact partially merged with) slightly weaker second pulses. These weaker pulses could either represent the slight time offset (asynchrony)of the emissionof pulses from thetwo timbals, thisthought tobe most likely,or aresecondary pulses producedby timbal relaxation ('OUT' clicks) of timbals, this thought to be less applicable due to the relatively strong development of these second pulses (see Fig.23C, D below).

FIGURE23.Xeropsalta aridula n. sp. Time expanded waveforms and complimentary envelopeplots oftwo selected segments of echemes. Figs. 23 A, B, recording near start of an echeme, showing the details of four macrosyllables, these each characterised by high amplitude pulses emitted at the end of each macrosyllable. Although each macrosyllable has six higher amplitude main pulses, the pulses show a marked tendency to occur in sets of 4 or 3 pulses. The initial smaller pulse of each macrosyllable is followed closely by a gap (0.8–0.9 ms) and then a set of 4 pulses. These pulse patterns are inferred to result from a slight offset (asynchrony) of pulse emissions between the two timbals, resulting in partial pulse overlaps and the groupingof pulses into 4 or 3sets,the startof each macrosyllable ismarked by 3 partially merged pulses.These 3-pulsesets are inferred to result from the complete overlap of a second peak with the following first peak, resulting in the higher amplitude central peaks. Figs. 23C, D are cage recordings, in which at the end of echemes, the normal 2-timbal song is modified by the cessation of one timbal, causing a drop of the RR of the pulse doublets by half. In these 1 timbal segments, the doublet pulses show the initial high amplitude pulse and following low amplitude peak (0.8–0.9 ms offset).One interpretation is therefore that the initial strong peak results from the timbal rib 1, the weaker peak from the flexing of ribs 2 to 5. The alternate explanation is that the second weaker peaks are the secondary relaxation 'OUT' pulses. Filtered A, B, to 1 kHz. C, D unfiltered.

FIGURE 24. Comparison of Xeropsalta aridula n. sp. song echemes in respect to: (A), waveform plot showing temporal structures; (B), spectrogram showing a dominant frequency band between approximately 7–11 kHz, with no frequency change during song emission; (C), amplitude spectra of complete phrase and the contained echemes, showing a relatively restricted band of emission between 6.6–10.5kHz, with the dominant frequency estimated to be 8.6 kHz.

FIGURE 30. Generalised map of central and northeastern Australia showing the distributions of the described Heremusina n. gen. andXeropsalta n. gen. species, as in Fig. 8, compared to the geography of selected river systems of inland Australia.The more heavily dotted lines show the systems draining towards the Lake Eyre Basin; the finely dotted lines of the rivers systems of the southeastern area of the Northern Territory are internally draining, not reaching beyond the State boundaries, while the river systems of northern and eastern Queensland, northern Northern Territory and NSW drain into the surrounding oceans.

FIGURE2. Lateralabdomen views of the five new species described in thispaper;(A), (B), Heremusina udeoecetes n. sp.and H. pipatio n. sp.; (C) to (E), Xeropsalta thomsoni n. sp., X. aridula n. sp., X.rattrayi n. sp., respectively.

FIGURE7. Pygofer and male genitalia,ventral views, respectively,of the five new species described in thispaper; (A), (B),H. udeoecetes n. sp. and H.pipatio n. sp.; (C) to (E), X. thomsoni n. sp. (see also Pl. 4), X. aridula n. sp., X. rattrayi n. sp. Sizes as in Fig. 6.