Oecanthus rubromaculatus Zefa, 2022

Zefa, Edison, Acosta, Riuler Corrêa, Timm, Vítor Falchi & Costa, Maria Kátia Matiotti Da, 2022, New species of tree cricket Oecanthus Serville, 1831 (Orthoptera: Grylloidea) from Southern Brazilian Atlantic Forest, with bioacoustics, Zootaxa 5155 (3), pp. 439-448 : 440-444

Oecanthus rubromaculatus Zefa , n. sp.

( Figs 1–2 )

Type material. Holotype ♂: Brazil, State of Rio Grande do Sul, municipality of São Francisco de Paula, São Francisco de Paula National Forest Conservation Unit , 29°25’26’’S, 50°23’11’’W, 02.iii.2022, Acosta , R.C. leg. MZUSP . Holotype condition: left leg III is detached, and maintained in holotype’s tube . Paratypes: same data of Holotype (02 ♂, 03 ♀, MZUSP) .

Etymology. Specific epithet refers to the light red spot present between eyes.

Diagnosis. Combination of the following characteristics: faint red spot at the vertex; metanotal gland median lobe triangular with apex curved upwards and forward; median lophi of pseudepiphallus slightly elongate, forming an open U-shaped invagination; posterior apex of the ectophallic arc distal prolongation U-bifurcated; and calling song with two distinct chirp rhythms.

Description. holotype male ( Fig. 1 ). Body slender, pale green with legs slightly yellowish from tibiae to tarsomeres. Head ( Figs 3–4 ): prognathous, pale-green, vertex with a reddish pale spot; clypeus and labrum pale-green; maxillary palpi pale-yellow and moderately elongate, first and second joints smaller than the other three, third to fifth joints subequal in size, latter a little longer, fusiform and apex depressed at inner side; joints of labial palpi paleyellow, with gradual increase in size toward apex; scape and pedicel marked by a longitudinal black line outlined in white; antenna flagellum pale-yellow, marked with spaced light brown rings, that become more intense toward at the apex; moderately prominent yellow eyes, ocelli absent. Thorax: pronotum longer than wide, posterior margin larger than anterior, dorsal disc pale-green, with lateral yellowish bands, slightly pubescent, bristles on the posterior border, lateral lobe little projected ventrally, posterior region more projected ventrally, tegmina translucent, longer than the abdomen; dorsal field surrounded with green veins; three poor marked cross-veins in the harp, and two in the mirror; hindwings well developed, projected beyond the tegmina. Legs: femora I, II and III apex marked with a little and poor marked black line in ventral face; femur III whitish green, pale yellowish at the apex, little shorter than the tibiae III; proximal region of the tibiae I, II and III marked with a little black dot in dorsal face; tibiae I and II unarmed; tibiae I proximal region swollen and mounted each side with an oval auditory tympanum, inner longer than outer; tibiae III serrulated, armed with four inner and three outer subapical spurs, and three outer apical spurs (the dorsal spine is twice the size of the median, which in turn is twice the size of the ventral spine) and four inner apical spurs (same arrangement as the outer spurs, with an additional dorsal spur a little longer than the ventral spur); tibiae’s spurs and spines tipped with black; tarsi I, II and III three-jointed, basitarsus longer than two others together, the middle joint is the smallest one. Abdomen ( Figs 5–6 ): tergites pale-green, cerci pale yellowish and slender, tipped with black; subgenital plate rounded posteriorly.

Discussion of paratypes. Subapical spurs: individuals 03FSFP ♀ and 4FSFP ♀ present four inner and three outer subapical spurs, same as holotype; and individuals 01FSFP ♂, 02FSFP ♂ and 05FSFP ♀ present three inner and three outer subapical spurs.

Right tegmen (paratype 02FSFP, Figs 10–11 ). Lateral field with 11 accessory veins; basal area reduced, including veins 1A, 2A, 3A; harp present three cross-veins; mirror with two straight cross-veins; apical area and median fan reduced. Vein Cu2 form the stridulatory file bearing 30 teeth.

Metanotal gland (paratype 02FSFP, Figs 12–14 ). Scutum ( Fig. 12 , Sc) with a pit wide, and a pair of protuberances ( Fig. 13 , Scp), each bearing a translucent tuft of bristles projected inward ( Fig. 14 , a), and a tuft projected posteriorly ( Fig. 14 , b); scutellum ( Fig. 12 , St) with a projected pair of protuberances ( Fig. 13 , Stp), and a posterior median lobe ( Figs 13 , pml, 14) triangular, with apex curved up and forward ( Fig. 13 , pml).

Male genitalia (paratype 02FSFP, Figs 15–19 ). Pseudepiphallic sclerite longer than wide; median lophi of pseudepiphallus (MLophi) projecting posteriorly, bilobed, forming an U-shaped invagination, lobe’s tip slightly arched outward; pseudepiphallic apodema present (PsAp), anterior margin curved posteriorly in dorsal view; rami (r) longer than pseudepiphallic sclerite, slightly curved inward, apex single, straight and not connected; ectophallic invagination well developed, ectophallic arc (arc) curved anteriorly, distal prolongation present (arcDp); ectophallic fold (EctF) slightly sclerotized; ectophallic invagination ventral projection (EctVp) very longer than ectophallic apodema (EctAp); endophalus U-shaped (End).

Female. ( Figs 2 , 6–9 ). Body color similar to male; slightly larger than male; light red spot between eyes little more intense than that of the male; subgenital and supra-anal plates as Figures 6 and 7 , respectively; ovipositor little shorter than the cerci, apex denticulate ( Figs 8–9 ).

Male and Female Measurements: in Table 1 .

Bioacoustics. ( Figs 20–24 , Tab. 2 ). Calling song is composed of a regular train of chirps (4 Ch/s), each one bearing 6 or 7 pulses (may occur 5 or 8 pulses) ( Figs 20, 23 ), interspersed by an irregular sequence of chirps, varying the number of pulses ( Fig. 21 ); both sound sequences present dominant frequency of 2.4 kHz at 18.4ºC ( Tab. 2 ). Courtship song is composed of chirps emitted sporadically throughout the courtship; chirps present 17.1 pulses ± 1.374 (15–19, n = 10); pulses increase in amplitude gradually ( Figs 22, 24 ); chirp duration = 0.22s ± 0.015 (0.2– 0.25, n = 10), and dominant frequency = 3.1 kHz ( Tab. 2 ).

Habitat and behavior. Males send the calling song in the tree canopy, up to about five meters from the ground; some individuals were chirping in the understory bushes, or even in lower branches, which made it possible for us to obtain some specimens for this work. Males stridulate on the leave’s edge ( Fig. 25 ), and use the leaf curvature to amplifier the acoustic signals. A couple was photographed on a leaf during copulation, with the male feeding the female from the metanotal gland secretions ( Fig. 26 ).

Figures

FIGURES 1–2. Habitus of Oecanthus rubromaculatus n. sp. in vivo. 1–male Holotype, dorsal view; 2–female paratype (05FSFP), dorsal view.

FIGURES 3–9. Male and Female morphological characteristics of Oecanthus rubromaculatus n. sp. after recent alcohol fixation. 3–Male head and thorax, dorsal views; 4–Male head, dorsal view; 5–Male subgenital plate, ventral view; 6–Female supranal plate, dorsal view; 7–Female subgenital plate, ventral view; 8–Ovipositor apex, dorsal view; 9–Ovipositor apex, ventral view.

FIGURES 10–11. Tegmen of Oecanthus rubromaculatus n. sp. 10–Right tegmen, dorsal view; 11–Stridulatory file with 30 teeth.

FIGURES 12–14. Metanotal gland of Oecanthus rubromaculatus n. sp. 12—Dorsal view; 13—Lateral view; 14—Metanotal gland posterior median lobe. Conventions: Sc—scutum; St—scutellum; pml—posterior median lobe; Scp—scutum protuberance; Stp—scutellum protuberance; a—tuft of bristles projected inward; b—tuft of bristles projected posteriorly.

FIGURES 15–19. Male genitalia of Oecanthus rubromaculatus n. sp. paratype 02FSFP. 15—apex of the genitalia, ventral view; 16, 17—phallic sclerites, ventral view; 18, 19— phallic sclerites, dorsal view. Conventions: MLophi—median lophi of pseudepiphallus; PsAp—pseudepiphallic apodema; r—rami; arc—ectophallic arc; arcDp—ectophallic arc distal prolongation; EctF—ectophallic fold; EctVp—ectophallic invagination ventral projection; EctAp—ectophallic apodema; End—endophalus.

FIGURES 20–24. Spectrogram of the calling and courtship song of Oecanthus rubromaculatus n. sp. 20—Sonogram of the calling song with regular train of chirps; 21—Sonogram of the calling song with irregular train of chirps; 22—Sonogram of the courtship song; 23—Oscillogram of the calling song; 24—Oscillogram of the courtship song.

FIGURES 25–26. Photographs of Oecanthus rubromaculatus n. sp. in the field. 25–Male stridulating at leaf edge. 26—Male feeding the female during copulation with secretions of the metanotal gland. Photos by Riuler Corrêa Acosta.