Oecanthus buxixu Acosta, Mendes & Zefa, 2024

Acosta, Riuler Corrêa, Mendes, Diego Matheus De Mello, Ramalho, Emiliano Esterci & Zefa, Edison, 2024, Oecanthus buxixu sp. nov. (Orthoptera: Grylloidea: Oecanthidae): A new species of tree cricket from Brazilian Amazon rainforest, Zootaxa 5492 (2), pp. 289-296 : 290-294

Oecanthus buxixu Acosta, Mendes & Zefa , sp. nov.

Figures 1–6, 8–10, 12–15 ; Table 1

Type material. Holotype ♂: Brazil, Amazonas , Maraã, Base Casa do Baré, 2°29’26.4”S – 64°42’32.2”W, 02.ii.2024, coleta manual, Mendes, D.M.M. leg. ( INPA) . Paratypes: 01 ( INPA), 01 ♂ and 01 ♀ ( IDSM), Ibid. 08.v.2024 .

Etymology. The specific epithet “buxixu ” refers to the popular name of the plant Clidemia japurensis , where the tree cricket is commonly found. It is a shrub native to South America, especially found in Brazil, Colombia, Venezuela, and Guyana. This plant is known for its small edible fruits and attractive flowers, which the tree cricket feeds on.

Diagnosis. Combination of the following characteristics: marks on scape and pedicel absent ( Fig. 4 ); calling song with 3 to 5 chirps/s, 6 to 20 pulses per chirp, and peak frequency 3.3 kHz, at 26ºC ( Figs. 16–19 ).

Description, holotype ♂ ( Figs 1–6, 8–10, 12–15 ). Coloration described in vivo. Body and other appendages light green. Head: prognathous, uniformly light green, including vertex, gena, clypeus, and labrum; dark eyes; ocelli absent; scape and pedicel without spots ( Fig. 4 ), same color as the flagellum; maxillary palps translucent green, moderately elongated, first and second palpomeres smaller than the other three, third to fifth subequal in size; last palpomere claviform, slightly curved at apex; labial palps light green, gradually increasing in size towards the apex. Thorax: pronotum longer than wide, posterior margin larger than anterior, dorsal disk pale green, with slightly whitish dorsolateral stripes; pronotum lateral lobe posterior more projected ventrally then the anterior region; tegmina translucent, longer than the abdomen; stridulatory file with 42 teeth; four cross veins in the harp, the smaller one poorly marked and curved; one cross veins in the mirror; well-developed hind wings, extending beyond the tegmina. Legs uniformly pale green; auditory tympana present in the tibiae I, the inner twice the size of the outer; tibia III slightly longer than femur III, serrulate, armed with four inner and three outer subapical spurs, and three outer and four inner apical spurs; spurs and spines of tibiae tipped with black; basitarsus longer than the other two tarsomeres combined. Abdomen: tergites whitish translucent, cerci light green, tipped with black, and reaching the length of the hind wings; subgenital plate rounded posteriorly; measurements ( Table 1 ).

Metanotal gland (Paratype ♂) ( Fig. 12 ). Scutum with a pair of protuberances, each one with two translucent tufts of bristles; scutellum with a pair of protuberances curved inward; posterior median lobe triangular, sclerotized, with apex translucent curved up and forward.

Male genitalia (Holotype) ( Figs 14–15 ). Pseudepiphallic sclerite: median lophi (MLophi) projected posteriorly, forming an V-shaped invagination; MLophi apex slightly curved outward; pseudepiphallic apodema (PsAp) anterior margin curved posteriorly in dorsal view; rami (r) long, slightly curved inward, apex single, straight and not connected each other; ectophallic invagination well developed, ectophallic arc (arc) curved anteriorly, distal prolongation present; ectophallic fold (EctF) poorly sclerotized; ectophallic invagination ventral projection (EctVp) longer than ectophallic apodema (EctAp); endophalus (End) U-shaped.

Calling song (Holotype, Figs 16–19 ). Under field condition: 3 ± 0.6 (2–4) chirps/s; chirp duration 0.28 ± 0.1 (0.05–0.81) s; interval between chirps 0.06 ± 0.03 (0.02–0.39) s; 9.1 ± 3.5 (2–26) pulses per chirp; peak frequency 2.9 ± 0.02 (2.92–2.96) kHz, at 24ºC. The first chirp has a higher number of pulses and exhibits a lower initial frequency and intensity (dB) ( Fig. 16 ). Under lab conditions: 3.5 ± 0.7 (3–5) chirps/s; chirp duration 0.3 ± 0.12 (0.15–0.53) s; interval between chirps 0.07 ± 0.02 (0.04–0.11) s; 11.2 ± 4.5 (6–20) pulses per chirp; peak frequency 3.1 ± 0.06 (3–3.3) kHz, at 26ºC. Similar to field conditions, the first chirp has a higher number of pulses and exhibits a lower initial frequency and intensity (dB) compared to the rest of the signal.

Female ( Figs 7, 11 , 21, 23 ). Body color similar to male, slightly longer than the male; tegmina slender and translucent; hind wings surpass the tegmina and cover the ovipositor and cerci; ovipositor as long as the cerci, apex denticulated; cerci pale green, tipped with black; supra-anal plate as Fig. 7 ; measurements ( Table 1 ).

Habitat and behavior. O. buxixu sp. nov. was found on the bush Clidemia japurensis ( Melastomataceae ), present in “Terra Firme” forests near the edge ( Fig. 24 ). In the locality, the bushes were around 2 m tall, and the tree crickets were found between 1.5 m and 0.5 m in height, in the abaxial part of the leaves. We found only one individual per leaf. Nymphs were seen both on the leaves, walking among the branches. Males stridulate on the lower part of the leaves, generally close to the edge, and they were very skittish when approaching them during the song, stopping the song and closing their wings quickly. Adults and nymphs were observed feeding on fruits ( Fig. 23 ) and leaves, indicating a close relationship between the tree-crickets and this plant. Despite extensive search in the locality, specimens of O. buxixu sp. nov. were only found on on bushes of Clidemia japurensis .

Figures

FIGURES 1–15. Male and Female morphological characteristics of Oecanthus buxixu sp. nov. after alcohol fixation. 1–3, Male in dorsal, ventral and lateral view; 4, Part of head in dorsal view, with scape and pedicel in ventral view; 5, Male terminalia in ventral view, showing subgenital plate and cerci; 6, Male supranal plate, dorsal view; 7, Female terminalia in dorsal view, showing supranal plate; 8, Tibia III serrulate, with four inner and three outer subapical spurs (*); 9, Tibia III apex, with three outer apical spurs (a, b, c); 10, Tibia III apex, with four inner apical spurs (d, e, f, g); 11, Ovipositor apex, ventral view; 12, Male metanotal gland, dorsal view; 13, Male right tegmina, ventral view; 14, Phallic sclerites, ventral view; 15, Phallic sclerites, dorsal view. Conventions: sp—scape, pd—pedicel, Sc—scutum, St—scutellum, pml—posterior median lobe, MLophi—median lophi of pseudepiphallus; PsAp—pseudepiphallic apodema; r—rami; Arc—ectophallic arc; EctF—ectophallic fold; EctVp— ectophallic invagination ventral projection; EctAp—ectophallic apodema; End—endophalus.

FIGURES 16–19. Spectrogram of the calling song of Oecanthus buxixu sp. nov. 16, Sonogram of the calling song registered in the field; 17, Sonogram of the calling song registered in the Lab.; 18, Oscillogram of the calling song registered in the Lab; 19, peak frequency.

FIGURES 20–24. Photographs of Oecanthus buxixu sp. nov. in the field. 20, Adult male; 21, Adult female; 22, Nymph f; 23, Adult female feeding; 24, shrub Clidemia japurensis (buxixu). Photos by Mendes, D.M.M.