Research Article Journal of Orthoptera Research 2019, 28(2): 137-143 Oecanthus mhatreae sp. nov. (Gryllidae: Oecanthinae): A new species of tree cricket from Mexico, with an irregular song pattern and unique chirp-like trill configuration NANCY ColLLiNs!, ISABEL MARGARITA CORONADO GONZALEZ2, BRUNO VICTOR ALFONS GOVAERTS? 1 Waterford, Racine County, Wisconsin, USA. 2 Fraccionamiento Vista Real, Corregidora, Querétaro, Mexico. Corresponding author: Nancy Collins (oecanthinae@gmail.com) Academic editor: Klaus-Gerhard Heller | Received 10 February 2019 | Accepted 15 April 2019 | Published 28 August 2019 http://zoobank.org/1BC2D39B-FB24-48D7-9240-72CCD090C27E Citation: Collins N, Coronado Gonzalez IM, Govaerts BVA (2019) Oecanthus mhatreae sp. nov. (Gryllidae: Oecanthinae): A new species of tree cricket from Mexico, with an irregular song pattern and unique chirp-like trill configuration. Journal of Orthoptera Research 28(2): 137-143. https://doi. org/10.3897/jor.28.33781 Abstract A new species of Oecanthus is described from Mexico. Oecanthus mhatreae sp. nov. occurs in central Mexico in the understory of tropical deciduous forest. Oecanthus mhatreae sp. nov. is currently known only from the Corregidora area of the Mexican state of Querétaro. The widened tegmina and chirp-like brief trills song are consistent with some members of the rileyi species group; however, this new species of tree cricket is different in several aspects. The chirp-like brief trills are generally irregularly spaced, it does not have the expected grouping of the chirp pulses, and the colors of buff, light olive green, or light brown are vastly different than the four known pale green species in the rileyi species group of the Western Hemisphere. Morphology, habitat, and song details of this new species, with the common name of Otomi tree cricket, are provided in this paper. Video can be viewed at www.oecanthinae.com. Keywords Cimatario, Corregidora, Natasha Mhatre, new species, Otomi, Querétaro, tropical deciduous forest Introduction According to the current listing on the Orthoptera Species File online (Cigliano et al. 2019), there are eight genera of Oe- canthinae worldwide, but only two occur in Mexico — Oecanthus and Neoxabea. The genus Oecanthus is comprised of 72 species, with ten of them occurring in Mexico (Walker 1967, Cigliano et al. 2019). Of the 23 species of Oecanthus in North America, Cen- tral America, and the Carribbean, 19 are divided into four main groups: nigricornis, niveus, rileyi, and varicornis (Walker 1967, Walker and Collins 2010, Walker 2019a). These groups can be distinguished by characteristics including: calling song character (chirping vs. trilling and continuous vs. intermittent); pulse or chirp rate at given temperatures; regular vs. irregular pattern of pulses or chirps; coloration of the antennae, head, pronotum, and abdomen; antennal markings on the pedicel and scape; and tegminal width. Oecanthines in the varicornis and nigricornis species groups have prolonged trilling songs (Walker 1963, 1967), while the niveus species group males sing in intermittent bursts of trilling (Walker 1962). In the Western Hemisphere, only the rileyi species group tree crickets have highly regular chirping songs (Walker and Collins 2010). Four chirping species in the rileyi species group of Oecanthus are currently known to occur in North America, Central America, and the West Indies: O. alexanderi Walker, 2010; O. allardi Walker & Gur- ney, 1967; O. fultoni Walker, 1962; and O. rileyi Baker, 1905. These four species have a chirping song with a grouping of pulses within each chirp, a pale green color with a white abdomen, and a round or oval mark on the pedicel and scape (Walker and Collins 2010). In 1965, RD Alexander recorded songs of eight unknown chirping oecanthines in Mexico. TJ Walker analyzed the record- ings (Walker and Collins 2010) and shared with NC that three songs had no pulse groupings in each chirp, questioning whether they might possibly be a new species group or clade. The chirp- like brief trills of this new tree cricket's song will be referred to as a chirping song for this paper. A 2019 photograph (Fig. 1) accompanied by a sound record- ing posted on iNaturalist.org (2019) by IMCG and BVAG from the central Mexican state of Querétaro, led to the investigation of this new species. NC recognized the calling song as a long-trained chirping pattern, but the light brown color with a milky buff pro- notum and light brown head was markedly different than other chirping species in North America. Materials and methods Habitat.—Specimens were found on private property of IMCG and BVAG in Fraccionamiento Vista Real, Corregidora, Querétaro, Mexico. The property is located adjacent to the Parque Nacional El Cimatario. The property sits on the southern slope of Cerro de Cimatario, an inactive volcano. The primary vegetation of this re- serve has been characterized as deciduous tropical forest, cactus shrub, reforestation, and pasture (Garcia-Garcia et al. 2008). After JOURNAL OF ORTHOPTERA RESEARCH 2019, 28(2) 138 construction activities on the private property, the disturbed lands were recolonized by some ruderal species while other parts were planted with herbs and ornamentals. BVAG monitored light intensity when the tree crickets were first heard singing over a five-day period. Light intensity measurements were used from online data in the Querétaro area (NWC 2019). Collection methods.—Areas inhabited by tree crickets were deter- mined both by manual searching and by locating actively singing males. Inhabited vegetation was then searched for adults of both sexes and nymphs. Specimens were collected in hand-held plas- tic containers. Photographs by BVAG, and sound recordings and specimen photographs by IMCG, were taken January-March 2019. Measurements were made after the specimens were euthanized by freezing. Specimens were preserved in 70% alcohol until deliv- ery to permanent depositories. Photographs were taken using a Samsung tablet and a Nikon D90 camera with a +4 Macro Close Up Neewer lens. Photographs, video, and sound recordings will be made available for viewing at Cigliano et al. (2019), iNaturalist (2019), and http://www.oecanthinae.com. The key from Walker (1967) was used for verifying the genus. Specimens were exam- ined for the presence/absence of spines on the hind tibiae. Acoustics. —Calling songs were recorded using recording app Grabadora Amazing MP3 with a Samsung tablet, with the tablet held as close to the singing tree cricket as possible. AVS4YOU Video Converter Software version 11.0 was used to convert MP4 to AVI. DoReMiSoft AVI to WAV Converter software was used to convert AVI files to WAV format. AVS4YOU Audio Editor Software version 6.1.2.375 and Raven Lite 2.0 were used to analyze the WAV sound tracks to make images of their waveforms and sound spectrums to measure the song frequency. Temperatures of the spots where tree crickets were singing were measured using a Taylor Sybron 5460 hand-held Mercury maximum minimum thermometer. Morphological measurements.—The total body length refers to the midline length from the fastigium to the apex of the subgenital plate, not including antennae, tegmina, limbs, or cerci. The tegmi- nal width was measured at the widest section, while resting atop the abdomen of the male. Pronotal length was measured along the medial line of the pronotum. The female’s ovipositor was measured from its base at the distal abdomen to the tip. Photo- graphs and measurements of the ovipositor, cerci, and metanotal gland, as well as counts of the stridulatory teeth, were made with the aid of a Jiusion Digital Microscope Model USB, magnification 40x to 1000x. Results Oecanthus mhatreae Collins & Coronado, sp. nov. http://zoobank.org/A2D3D82F-C1A6-43BD-B795-FFFB2FA652E2 Etymology.—Specific epithet in honor of Natasha Mhatre, who has worked extensively with Oecanthinae and has published many articles focusing on acoustic communication. The pronunciation of mhatreae is MAT-ray-ee [MAT] [ra] [-ee]. The common name, Otomi tree cricket, is after the Otomi, an indigenous people of Mexico inhabiting the central Mexican Plateau region. Type verification.—The genus Oecanthus was determined by the presence of spines on the hind tibiae. N. COLLINS, ILM. CORONADO GONZALEZ AND B.V.A. GOVAERTS Type material.—MEXICO, holotype <, alcohol vial, Querétaro, Cor- regidora, Fraccionamiento Vista Real, 20°52'20"N, 100°38'80"W; elevation ca 2130 m, understory of tropical deciduous forest, I. Coronado leg., 24 Jan 2019, deposited at Universidad Nacional Autonoma de Mexico (UNAM), Mexico City. Paratypes: 1 9 and 1 4, 23-24 January 2019, and 1 9 and 1d 13 February 2019, same location as holotype, deposited at UNAM. Male holotype description and measurements.—(in mm). Light olive green wings with dark staining along some veins. Pronotum milky buff color. Grayish tan head with four lighter streaks running to pronotum, and light pink patch near scapes. Pedicel and scape pale green. Antennae pale greenish white. Eye color purplish. Pal- pi translucent tan. Oval black mark on each pedicel and scape. Abdomen light olive green with scattered darker blotches. Femurs translucent olive green; tibiae and tarsi light olive green. Body length 13.5; tegminal length 13.7; tegminal width 6.8; pronotal length 2.2; distal pronotal width 2.4; hind femur length 10; cerci 4.9. The stridulatory file length is 1.5 mm, and the stridulatory teeth count is 36. Characters.—Overall color of both sexes can range from light brown (Fig. 1) to light olive green (Fig. 2). Tegmina with dark staining along veins. Head grayish or brownish with small patch ranging from pink to peach. All individuals have four lighter colored vertical streaks on the distal portion of the top of the head extending to under the pronotal shield (Fig. 3). The light brown individuals are not believed to be a true brown form of this species as the pronotum is equally buff colored to the pronotum on the olive green individuals. The patch of color on the head is located even with and just behind the scape. Pedicel and scape colors vary from whitish to greenish to brownish. Ventral surface of pedicel and scape each with one oval black mark (Figs 4, 5). The black mark is situated on a whitish field; however, dead specimens dark- en and the white may not be readily visible. Antennae filaments translucent greyish white or tan. Eye color purple to brown. Palpi translucent tan. Pronotum has a milky or creamy buff or light olive color (Figs 1-3, 6). Tympanal mem- brane on fore tibiae whitish. Ventral abdomen with scattered, slightly darker blotches and speckles; color varies from light olive, buff or tan (Fig. 7). Tarsi light olive or light brown, tibiae olive or tan, femora translucent light olive green or tan. Some individuals with whitish area at ventral femoral-tibial joints. Cerci straight and pale, extending beyond the distal edge of the tegmina. Hind wings do not extend beyond distal edge of tegmina. The metanotal gland photo (Fig. 8) was taken of a dead specimen, and this species dark- ens from freezing euthanasia. Right tegmen stridulatory file as in Fig. 9 with 32-36 teeth; file length 1.4-1.7 mm. Paratype males measurements: Body length 12.4-13.0; wing length 11.0-12.0; wing width 5.8-6.9; pronotal length 1.5-2.8; distal pronotal width 2.0; hind femur length 7.0-8.2; cerci length 4.3-5.0. Paratype female measurements: Female with matching anten- nal markings and coloring as males. Body length 12.5-12.8; wing length 11.5-12.0; wing width 3.0-3.1; pronotal length 1.9-2.5; distal pronotal width 1.8-2.0; hind femur length 7.5-8.8; cerci length 6.5-6.6; ovipositor length 6.25-6.5. Ovipositor extends slightly beyond the tips of the cerci (Fig. 10). Nymphs as in photos of 3-5" instars (Figs 11-13). JOURNAL OF ORTHOPTERA RESEARCH 2019, 28(2) N. COLLINS, ILM. CORONADO GONZALEZ AND B.V.A. GOVAERTS 139 Figs 1-5. Oecanthus mhatreae sp. nov.: 1. Light brown male. 2. Light olive tone male. 3. Adult female head and pronotum. 4. Antennal markings on holotype male. 5. Antennal markings on paratype female. Habitat.—Tree crickets were found on ten plant species: Anisacan- thus pumilis (F. Dietr.) Nees; Cnidoscolus multilobus (Pax) I. M. John- ston; Colubrina triflora Brogn. Ex Sweet; Croton ciliatoglandulifer Ortega; Dasilyrion parryanum Trel; Iresine cassiniliformis S. Schauer; Justicia candicans Nees L D Benson; Ruta graveolens L; Senecio salig- nus DC.; and Thunbergia alata Bojer ex Sims (Martinez and San- doval 2017). Of these plants, R. graveolens, C. multilobus, and T. alata are introduced species. The only plants Otomi tree crickets were witnessed as actively feeding upon were C. ciliatoglandulifer, a native plant, and on C. multilobus and T. alata, which, unlike the native vegetation, are evergreen plants (Calder6n de Rzedowski and Rzedowski 2001). Climate.—According to records on the National Water Commis- sion website, rainfall totals for Querétaro were (listed in mm from January 2018 through March 2019): 9.2, 10.0, 2.8, 24.1, 39.5, 161-8,,3124, 7157, 10:2) .5826;-31, 173-8, 7.5;.2.3,-and4-6. bhelow= est temperatures occurred in January 2018 (5.3°C in 2018 and 8.5°C in 2019). The warmest temperatures from January-March 2019 were 24.7°C, 28.1°C, and 29.6°C. Behavior.—Light intensity readings ranged from less than 5 W/m? to 12 W/m’ at the time males began singing. Song monitoring in January and February revealed Otomi tree crickets began singing from one minute before to eleven minutes after sunset and were singing within 10 minutes of sunset in temperatures of 17-18°C and past midnight in temperatures less than 12°C. The holotype male and one paratype female were video recorded mating while in captivity. A video clip can be viewed at www.oecanthinae.com. Calling song.—The song pattern and chirp configuration of Otomi tree cricket were instrumental in diagnosing this new Mexican oecanthine. Waveform analysis showed that each chirp was com- prised of a long string of pulses with no groupings (Figs 14-16). The recordings taken in the field and in captivity by IMCG were at temperatures of 14°C-19°C. The carrier frequency of the calling song at 17°C was slightly above 2.6 kHz (Fig. 17). One recording revealed the intermittent long chirp song of interest with a faster chirping species in the background (Fig. 18). The faster chirping was 3-4 times faster than the long chirping of this new species, affirming the slow rate of the target species while the highly regu- JOURNAL OF ORTHOPTERA RESEARCH 2019, 28(2) 140 N. COLLINS, ILM. CORONADO GONZALEZ AND B.V.A. GOVAERTS Figs 6-9. Oecanthus mhatreae sp. nov.: 6. Singing male showing buffy pronotum (on native plant Dasilyrion parryanum Trel.). 7. Adult female showing blotching on ventral abdomen. 8. Metanotal gland. 9. Stridulatory file and teeth. Fig. 10. Adult female coloring and ovipositor length (on non-na- tive Ruta graveolens L.). lar spacing of the background singer affirmed the irregular pat- tern of Otomi tree cricket. The irregular chirping pattern and the ungrouped chirp configuration of this new species were compared to the patterns and configurations of four other chirping species, two intermittent trilling species, and one continuous trilling spe- Figs 11-13. Oecanthus mhatreae sp. nov.: 11. Abdomen pattern of 3" instar nymph. 12. Female 4" or 5" instar nymph. 13. Male 4" or 5" instar nymph. cies (Fig. 19). The four chirping species in the rileyi species group display grouping of their pulses. Oecanthus varicornis, from the varicornis species group, has continuous trilling with runs of pulses over several seconds, while O. mhatreae sp. nov. chirps never exceed 0.7 second. Of the three JOURNAL OF ORTHOPTERA RESEARCH 2019, 28(2) N. COLLINS, ILM. CORONADO GONZALEZ AND B.V.A. GOVAERTS HHH Figs 14-16. Waveforms of the calling song of O. mhatreae sp. nov. at 17°C: 14. Chirping for 15 seconds. 15. Three chirps. 16. A sin- gle chirp (0.5 sec duration) with 26 ungrouped pulses. fe) Semin G:C manahre wt NT wm haa aie annel| Begin Time | End Time | Low Freq] High Freq] Della Time] Delta Freq | Avg Power Density| Annotation | (s ( Hy | ty | sy | (s) | _ BFE 0.0) A 0.0] “78 0.0] -19.6) (s) Fig. 17. Audio recording of the calling song of O. mhatreae sp. nov. at 17°C showing a carrier frequency of slightly above 2.6 kHz. intermittent bursts of trilling species, O. niveus has a J-shaped mark on the scape (Walker 1962). The second species, O. exclamationis, has markings on the pedicel and scape that resemble an inverted exclamation mark (Fulton 1915). The third intermittent bursts of trilling species, O. leptogrammus, does have an irregular pattern similar to O. mhatreae sp. nov.; however, the coloring and antennal markings are markedly different for these two species. Oecanthus leptogrammus is very pale green (Collins et al. 2014) and has a thin black line on each pedicel and scape (Walker 1962). At all temperatures, the chirping pattern of Otomi tree crick- et was irregular. This sporadic rate and pattern were unlike any of the other known chirping species in North America. Fig. 20 shows the irregular rate at a variety of temperatures and includes a sample of the early evening warm up song heard most evenings. Since Otomi tree cricket has an irregular chirping pattern, a trend line graph cannot reliably be used for comparison with chirpers with regular patterns. The chirp rate at recorded temperatures was plotted for comparison to the other known songs (Walker 2019b, Cornell Lab 2019) of North American chirping species (Fig. 21, Table 1). The graph displays the general niche that each of these five species occupy. 14] HHH Fig. 18. Calling song recording of O. mhatreae sp. nov. at 17°C. The clip was amplified to highlight the background song. This 30- sec clip shows the irregularly spaced O. mhatreae sp. nov. chirps at a rate of 28 pulses per minute with a yet to be determined chirping species in the background with a highly regular pattern at a rate of 100 chirps per minute. single Chirp Multiple Chirps 0. allardi 26.6 C 47 sec O. alexanderi 23.4. 12 sec 19¢ i? sec O. mhatreae é 20,2 C 12 sec H4HH-HH4HH-+-+4+-H1 20.5 © 17 sec O. fultoni “HE HEHEHE Single Burst Bursts of Trills O. leptagrammus