Heremusina, 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 : 4-15

Genus HEREMUSINA n. gen.

Figs. 2A – 7A , 2B – 7B , 8 , 12–17 , 30 ; Pl. 1, 2.

Etymology: Derived from Latin, a feminine construct of the masculine Heremus, referring to wilderness/desert/ wasteland, which broadly describe the environments of the two new species described.

Distribution ( Fig. 8 ): Northern Territory in the regions around Alice Springs, extending westwards to Hermannsburg, and northern Queensland in the Cloncurry region, north and south of Cloncurry township.

Diagnosis: Head: Outer margins of eyes approximately as wide as mesonotum; supra-antennal plate meeting eye; postclypeus outline rounded across ventral midline; in lateral profile gently rounded between 'top' and 'sides'. Thorax: Pronotum in dorsal view parallel-sided; pronotal collar width at dorsal midline much less than diameter of eyes; paranota confluent with adjoining pronotal sclerites, no mid lateral tooth; cruciform elevation wider than long; epimeral lobe not reaching operculum; metanotum clearly visible at dorsal midline. Fore wings hyaline, with 8 apical cells; subapical cells absent; ulnar cell 3 angled to radial cell; basal cell clearly longer than narrow; costal vein higher than R+Sc; costa nearly parallel-sided to node, very slight widening at node; costa almost straight with only minimal curvature; pterostigma with pale brown infuscation; vein CuA with gentle curvature, with the cubital cell larger than medial cell; veins M and CuA meeting basal cell with their stems fused as one; vein RA1 not completely aligned with Sc for its full length, slightly diverging subapically; vein CuA1 divided by cross-vein mcu, the two segments of similar length; veins CuP and 1A fused for most of their length; distance between cross veins r and r-m approximately equal to distance between r-m and m; apical cells 3 to 6 more or less equal to lengths of ulnar cells, some slightly shorter, some slightly longer; radial cell shorter than distance from its apex to wing tip; wing outer margin clearly developed for its total length. Hind wings with 3 to 4 apical cells, mostly 4; no infuscation on ambient vein; width of 1 st cubital cell at distal end more than twice that of 2nd cubital cell; anal lobe narrow with vein 3A curved, separated from wing margin for most of its length. Male opercula: Relatively broad and bulbous in ventral view, mostly reaching margin of timbal cavity, excepting between lateral margin and crest; distal margin very broadly rounded; margins raised above level of tympanal cavity; basal plate strongly domed and relatively large; opercula not reaching across abdomen. Male abdomen generally bulbous, most strongly developed around tergites 2 to 4 and sternites II to IV, clearly wider than thorax; tergites in cross-section somewhat tent-like, dorsally straight, curved ventrally; epipleurites reflexed ventrally from junction with tergites; tergite 1 narrowed along dorsal midline; tergite 2 slightly wider than tergite 3 along dorsal midline; sternites in cross-section convex, relatively swollen so that in lateral view are mostly at least partially visible. Timbals with 3 continuous long ribs with long ribs 1 to 3 unbroken, relatively similar in length, each unfused ventrally, and spanning the full height of timbal; long ribs 1 to 3 fused dorsally to basal spur; rib 4 very thin medially, and not always clearly seen to be continuous across timbal, ventrally and dorsally unfused; rib 5 (most posterior) short; 3 to 4 intercalary ribs, these very thin and not easily seen; basal dome bulbous, narrow, somewhat lens-like; the outer anterior area to basal dome broad and gently undulating; anterior area of timbal dominantly occupied by ribs; timbals not extended below wing bases; timbal covers absent.

Male genitalia. Pygofer in ventral view ovoid in shape, with upper pygofer lobes widest points, the shape generally tapered from upper pygofer lobes to base; pygofer with distal shoulders developed; upper lobes moderately well developed, narrow and gently curved in ventral view, set well removed from dorsal beak; gently rounded in lateral view; basal lobes undivided, well developed, partially rounded in lateral view, abutted against pygofer margin; dorsal beak elongated as a pointed apex, forms part of chitinised pygofer. Uncus relatively short, somewhat flattened, median lobe gently curved in ventral view, roughly tongue-shaped. Claspers well developed, restraining aedeagus; prominent in lateral and ventral views, terminal claw with minimal cavity developed ventrally, terminations widely separated; gently rounded inward-facing swelling present on inner margins, apices diverging, in ventral view the widest dimension of claspers. Aedeagus with basal plate in lateral view undulated, depressed on dorsal midline, in dorsal view short and broad, apically broadened with 'ears', much broader than long; basal part of basal plate directed forwards away from thecal shaft, ventral rib fused with basal plate, small functional 'hinge' compressed between theca and basal plate; thecal shaft almost straight and parallel-sided, relatively thickly developed; pseudoparameres present, developed sub-apically, lateral of theca, to which they have fused for at least part of their length, in dorsal view their apices widely separated, diverging throughout their length, in lateral view directed upwards beyond thecal shaft; endotheca not visible; ventral support absent, thecal apex chitinised, thecal subapical cerci, flabellum and conjunctival claws each absent; vesical opening apical on theca.

Distinguishing characters between Mugadina and Heremusina n. gen. The above listing of the generic characters of Heremusina n. gen. extensively follows those defined by Moulds (2012) for Mugadina , thereby emphasising the closeness of many of these characters to those of Mugadina s.s. Although the lateral abdomen shapes of Mugadina and Heremusina n. gen. are somewhat similar ( Figs. 1A, B and 2A, B ), significant differences are seen in the general shapes of the genitalia (cf. Figs. 1C–F , and Figs. 6A–B and 7A–B ), the pygofer outlines being more elongated in lateral and ventral views in Heremusina n. gen. The dorsal beaks are more elongated and gently curved in Herumusina n. gen.; the claspers exhibit sharply diverging distal terminations in Mugadina , contrasting with Heremusina ; marked differences in opercula outline shapes are evident ( Figs. 1I, J compared to Figs. 3A, B ), noting the broader and more blunted and rounded terminations (between the medial and distal margins) of the Heremusina n. gen. opercula; the intercalary timbal ribs of Heremusina n. gen. are unusually thin, and the ventral terminations of long ribs 1 to 4 are clearly separated in Heremusina n. gen. as compared to Mugadina ( Figs. 1G, H compared to Figs. 4A, B ); the 4 hind wing apical cells in Heremusina n. gen. compared to the 4 to 5 in Mugadina . As shown below, the calling songs have markedly differing structures.

Figures

FIGURE 1. Mugadina emma and M. marshalli, comparison of selected morphological characters of both species. (A), (B), lateral views of abdomen. (C), (D), lateral views of male genitalia, both lengths 1.9 mm. (E), (F), ventral views of same genitalia; (G, H), timbals; dorsal to right, and (I), (J) left opercula. Figs. C, D based on specimens from 4 km north of Amby, southern Queensland and Figs. D, F from Lake Broadwater, southeast Queensland. Figs. A, G, I, based on specimens from Boonah, southeastern Queensland and Figs. B,H, J from Drillham, southern Queensland.The scale bars represent 1 mm.

FIGURE 3. Male opercula, all left opercula, of the five new species described in this paper; (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. Opercula nomenclature shown in (E).

FIGURE 4. Left timbal, posterior margin to right, dorsal margin at top, of the five new species described in this paper; (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. For clarity, only selected long ribs and one short (intercalary) rib are labelled, as are the timbal plate and apodeme.5 long ribs are present, only numbers 1 and 5 labelled.

FIGURE 6. Pygofer and male genitalia, lateral views, respectively, of the five new species described in this paper; (A), (B), Heremusina udeoecetes n. sp. and H. pipatio n. sp.; (C) to (E), Xeropsalta thomsoni n. sp. (see also Pl.4), X.aridula n. sp., X. rattrayi n. sp. Pygofer lengths are, respectively, 1.60, 1.70, 1.86, 1.91, and 1.9 mm.

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 12. Heremusina udeoecetes n. sp. Waveform plots, based on field recordings at 11 km N.W. along Tanami Desert Road, 20 km north of Alice Springs, in low grassland. Figs. A, D show the characteristic repeated echemes, these having durations ranging between 272–332 ms, each commencing with 2–9 isolated pulses, followed by a sequence of closely spaced pulses; an isolatedpulse isemitted at end of each echeme.Figs.B, Dare time expandedwaveform plots showingmore detail of the pulses. The initial pulses (Fig. B) are isolated pulses, these changing to doublet pulses within the continuous echeme segment.Pulses (including doublet pulses) have repetition rates varying between 160–193 Hz. (C), shows the final segment of an echeme in which the pulses alternate between single and double pulses, followed by the single isolated final pulse. Filtered to 3.5 kHz.

FIGURE 13. Heremusina udeoecetes n. sp. Time expanded details of selected pulses shown in Fig. 12, shown as waveform and companion envelope plots. In 13A, B, the initial single pulse is markedly of longer duration compared to each of the following double pulses, suggesting that it results from a partial overlapping of asynchronous pulses from the two timbals; the double clicks are therefore interpreted as temporally more clearly separated pulses emitted by the two timbals.Figs 13C, D are strongly developed doublet pulses, emitted asynchronously by the two timbals. The following smaller peaks which are almost coalesced with the main peak are believed to represent the emission from timbal ribs 2–5. The peaks labeled 'S' are interpreted to be secondary ('OUT') clicks of the timbals, not seen following first peak most likely as they overlap the emission of the second primary peak of each doublet. Fig. 13E, F, time expanded single pulses emitted at start of echeme, these showing merged weaker peaks (probably emissionsof ribs 2–5).Secondary peaks, marked 'S', occurring 1.7ms after the primary peaks, are inferred to represent be 'OUT' clicks of the timbals.Filtered to3.5 kHz.

FIGURE 14. Heremusina udeoecetes n. sp., waveform (A, B, D) and envelope (C, E) plots from parabola recordings made 3 km east of Hermannsburg, N.T., ~112 km WSW of Alice Springs; 14A shows an echeme segment with two initial isolated pulses, followed by rapidly repeated doublet pulses, the PRR measured at 192 Hz. Figs.14B, C, are time expanded plots of the pulse doubletsshowing both thepeaks tobe stronglydeveloped, witha weak secondary peak1.5 ms followingthe second peak, evidently not so clearly developed after the first peak (the doublet inferred to be emitted asynchronously from both timbals); Fig.14D, E illustratessingle pulses occurring at startof echeme showing only weakly developed secondary peaks(marked 'S'). These plots also shows small but increasingly stronger peaks (arrowed) almost joined to the preceding primary peaks, these thought to represent the initial development of doublet peaks (i.e. increasing asynchrony of timbal emissions). Filtered to 7.5 kHz (A), and 9 kHz (B to E).

FIGURE15. Comparison of Heremusina udeoecetes n. sp. song in terms of, (A), waveformplot (temporalstructures of song), (B),spectrogram showing timbal emissionfrequencies, these concentrated inrange ~11–17 kHz, but exhibiting no indication of systematic changes of frequencies during song emission, although minor frequency disturbances may occur at the start of each echeme; and (C), amplitude spectrum showing the dominant frequency envelope between 11.5–16.8 kHz, with the estimated dominant frequency at 13.9 kHz.Filtered to 3.5 kHz (A), and 7.5 kHz (C).

FIGURE 16. Heremusina pipatio n. sp. song, field recording from ~15 km N. of Cloncurry, N.W. Queensland. Fig. 16A is a waveform overview showing the structure of the echemes which comprise sets of closely spaced single pulse emissions, without any isolated single pulses at the start of each echeme (except at the beginning of anew songsequence, as shown in this segment). Each echeme is followed with an isolated single pulse. The echeme durations (52–63 ms) are clearly shorter than those of H. udeoecetes n. sp., and the resulting echeme repetition rates therefore higher (9.2–10.7 Hz). Pulse repetition rates withinthe echemes range between 180–225 (mean207) Hz.Fig.16B, C, time expanded waveform plot of a single echeme, and the following isolated pulse, showing the pulses to be single pulses, presumably emitted by the alternation of the timbal contractions; Fig. 16C, D, higher resolution, time expanded waveform and envelope plots of three echeme pulses showing the initial high amplitude peaks immediately followed, without a gap, by weaker peaks, inferred as ribs 2–5 emissions. Well developed, isolated secondary peaks (marked as 'S') occur 1.7 ms following the preceding main peaks, these inferred to be secondary, relaxation ('OUT') pulses of the timbals. Filtered to 1 kHz.

FIGURE 17. Comparison of Heremusina pipatio n. sp. songs in relation to; (A) waveform plot showing temporal pulses structures; (B), spectrogram, showing a dominant frequency band between ~10 to 18 kHz, without significant frequency shift during the song; and (C), amplitude spectra showing the clearly developed frequency envelope between 10.7–18 kHz, with the dominant frequency estimated at 14.0 kHz, located at the low amplitude centre of the frequency envelope.Filtered to 1 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.