Research Article Journal of Orthoptera Research 2021, 30(1): 7-16 Oecanthus rohiniae sp. nov. (Gryllidae: Oecanthinae): A new chirping tree cricket of the rileyi species group from Mexico NANCY CoLLiINs!, ISABEL MARGARITA CORONADO-GONZALEZ2, AURORA Y. ROCHA-SANCHEZ?, BRUNO GOVAERTS?, WILBUR HERSHBERGER* 1 Waterford, Racine County, Wisconsin, USA. 2 Fraccionamiento Vista Real, Corregidora, Querétaro, Mexico. 3 Hospital Regional de Alta Especialidad de Ciudad Victoria “Bicentenario 2010”, Victoria, Tamaulipas, Mexico. 4 Hedgesville, Berkeley County, West Virginia, USA. Corresponding author: Nancy Collins (ycnancy2k@hotmail.com) Academic editor: Klaus-Gerhard Heller | Received 10 January 2020 | Accepted 23 June 2020 | Published 18 February 2021 http://zoobank.org/453DAF66-5CC1-4CC9-8 70E-2EDD98BFDE52 Citation: Collins N, Coronado-Gonzalez IM, Rocha-Sanchez AY, Govaerts B, Hershberger W (2021) Oecanthus rohiniae sp. nov. (Gryllidae: Oecanthinae): A new chirping tree cricket of the rileyi species group from Mexico. Journal of Orthoptera Research 30(1): 7-16. https://doi.org/10.3897/jor.30.50039 Abstract A new species of Oecanthus is described from Mexico. Oecanthus rohini- de sp. nov. occurs in central Mexico in the understory of tropical deciduous forest and is currently known only from Mexico. This new species has the coloring, antennal markings, slightly widened tegmina, and calling song that are found in the rileyi species group. Although morphologically very similar to Oecanthus fultoni, the shapes of the distal hooks on the male copulatory blades differ between the two species. There are also differences in the song pulse patterns and chirp rate response to temperature. This new species has been given the common name Cri-Cri tree cricket. Video and song recordings are available online. Keywords bioacoustic, biodiversity, Querétaro, tropical deciduous forest Introduction According to the Orthoptera Species File (Cigliano et al. 2020), the subfamily Oecanthinae Blanchard, 1845, is represented by nine genera: Oecanthodes Toms & Otte, 1988; Oecanthus Serville, 1831; Viphyus Otte, 1988; Leptogryllus Perkins, 1899; Prognatho- gryllus Brunner von Wattenwyl, 1895; Thaumatogryllus Perkins, 1899; Neoxabea Kirby, 1906; Xabea Walker, 1869; and Paraphasius Chopard, 1927. Two of these genera occur in Mexico—Oecanthus and Neoxabea. Twenty of the species of Oecanthus in North Ameri- ca, Central America, and the Caribbean are divided into four main species groups: nigricornis, niveus, varicornis, and rileyi (Walker 1962, 1963, Walker and Collins 2010, Singing Insects of North America 2020b). These groups can be distinguished by characteris- tics including song type (chirping vs trilling and continuous vs in- termittent); song 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 (Walker 1962, 1963, Walker and Collins 2010). Four species in the rileyi species group are currently known to occur in North America, Central America and the Ca- ribbean (Walker 1967, Collins et al. 2014): O. alexanderi Walker, 2010 (Walker and Collins 2010); O. allardi Walker & Gurney, 1960; O. fultoni Walker, 1962; and O. rileyi Baker, 1905. In 1960, Walker and Gurney published the description of O. al- lardi and included details of ten specimens of snowy tree cricket from Tamaulipas and Michoacan, Mexico. In 1965, Richard D. Alexander traveled throughout Mexico and recorded Orthoptera and other singing animals. Notes from his recordings include six tapes that mention ‘fultoni’ with adjectives such as slow, fast, and grouped or not grouped (Suppl. material 1: historical recordings). No further investigations of chirping tree crickets are known to have occurred in Mexico until the description of O. mhatreae Col- lins & Coronado, 2019 (Collins et al. 2019). In 2019, a photograph accompanied by a sound recording (iNaturalist 2020) posted on iNaturalist.org from the central Mexican state of Querétaro led to the investigation of a new spe- cies of Oecanthus tree cricket. The chirping song pattern, widened tegmina, and orange area on the head are characters found in the rileyi species group. Although other photos from Mexico of tree crickets resembling the rileyi species group have been posted on iNaturalist, none had previously been accompanied by recordings of their songs. After reviewing all material, it was discovered that the samples did not correspond to any of the described taxa. This paper describes a new species of Oecanthus collected in Querétaro. Material and methods Specimens.—Adults and nymphs of Oecanthus were collected from a private property and immediate surrounding areas of Fracciona- miento Vista Real, Corregidora, State of Querétaro, Mexico. This locality is near Parque Nacional El Cimatario, on the southern slope of Cerro de Cimatario. Specimens were initially located by the song of the males and collected manually. Females and JOURNAL OF ORTHOPTERA RESEARCH 2021, 30(1) 8 N. COLLINS, ILM. CORONADO-GONZALEZ, A.Y. ROCHA-SANCHEZ, B. GOVAERTS AND W. HERSHBERGER nymphs were found in the same area. Tree crickets were brought indoors in plastic containers (15 x 15 x 20 cm) with holes on the side for ventilation. The males and females were kept alive and separated to be recorded and then preserved in 70% ethyl alcohol for morphological studies. Photographs and measurements of di- agnostic characters were made with a Jiusion Digital Microscope Model USB, magnification 40x to 1000x (ovipositor, cerci, and metanotal gland), MOTIC-SWZ168739 stereo-microscope at 40x and equipped with a 10 mp digital camera (internal genitalia). Characters considered for description are as follows: body length, head colors, antennal colors and markings, pronotum in dor- sal view, tegmina length and width, stridulatory file, metanotal gland, cerci, subgenital plate, and internal genitalia (copulatory blades). Additional characters for females included the oviposi- tor, subgenital plate and cerci. The following measurements were made: body length—from the tip of the labrum to the apex of the subgenital plate; pronotum length (from anterior to poste- rior margin along midline); pronotum width (at the widest distal portion in dorsal view); tegmina length (from the thorax joining point to distal end of tegmina along midline); tegminal width (measured at the widest section of tegmina at rest); hind femur length; and cerci length. The females’ ovipositors were measured from the base (closest portion to the abdomen) to the distal tip. Copulatory blades (Fulton 1915) project from the male genitalia complex and are situated just above the subgenital plate. These genitalia structures have also been referred to as pseudepiphallus (Chopard 1961, 1969), lophi medians [middle lobes] (Desutter 1987), or main lobe of pseudepiphallus (Zefa et al. 2012). The genitalia of Mexican specimens were treated with an aqueous so- lution of 10% potassium hydroxide (Rocha-Sanchez et al. 2018, Barrientos-Lozano and Rocha-Sanchez 2013). No chemicals were used on the O. fultoni specimen from the USA. Genus determina- tion was made with keys from Walker (1967) and SINA (2020a) and review of taxa of Oecanthus in the Orthoptera Species File (Cigliano et al. 2020). Calling song recording and analyses.—The male acoustic signal was recorded in the field and indoors using a Samsung Galaxy Tab S4 tablet model SM-T830, the app Grabadora Amazing, and a Mix- Mart 8 GB, PCM, 1536 kbps digital voice recorder. Audio devices were tested for calibration by recording a reference time audio file with reference tones and comparing the results to the original file. The recording devices were kept at a distance of approximately 10 cm from the individual. Analyses of song recordings were made with the Raven Pro 1.6 program (Cornell Lab 2020). Audio wave- forms were created using the programs Raven Lite 2.0 or Raven Pro 1.6 (Cornell Lab 2020). Grouped pulse patterns were determined by counting individual pulses within each chirp. A chirp consists of varying numbers of pulses, and each pulse corresponds to a single closure of the tegmina (Walker and Collins 2010). Ten ran- domly chosen chirp periods were measured for each recording to determine the chirps per minute rate for that sample. Additional recordings (Suppl. material 2: source recordings) from the Macau- lay Library of Cornell Lab (2020) were used for the preparation of two graphs to compare chirps per minute vs temperature and car- rier frequency vs temperature, with additional species in the rileyi group. Regression lines for the sampled O. rohiniae sp. nov. popu- lation were calculated in Microsoft Excel for Mac, Version 16.16.22 (200509) (2016). The slopes of the regression lines for O. rohiniae sp. nov. and O. fultoni were compared using the t-test procedure for paired samples from Wonnacott and Wonnacott (1977). Climate.—Temperatures were measured using an ELMECO DTM2 digital thermocouple thermometer with a range of -50°C to 1000°C, with an accuracy of 0.1°C. Ambient temperature and rainfall ranges [climatologia/temperaturas-y-lluvias/resumenes- mensuales-de-temperaturas-y-lluvias] for 2018 and 2019 were tak- en from the National Water Commission weather website (NWC 2020). The light intensity was determined using a HIOKI model 3422 digital luxmeter with a range of 0 to 2000 Lx (1Lx accuracy) and using data from the NWC website. Results Oecanthus rohiniae Collins & Coronado-Gonzalez, sp. nov. http://zoobank.org/EE607E6F-B950-4FDF-BCAO-742177F85FD4 Material examined.—Holotype: MEXICO e 3; Querétaro, Corregi- dora; 2130 MASL; 30.xi.2019; 20°52'20"N, 100°38'80"W; I. Coro- nado leg.; deposited Universidad Nacional Autonoma de México (IB-UNAM). Paratypes: MEXICO ¢ 2 3, 3 9; same locality as ho- lotype; 2 6, 2 2 deposited Tecnolégico Nacional de México-Insti- tuto Tecnoldgico de Ciudad Victoria (TecNM-ITCV); 19 deposited IB-UNAM. Etymology.—Specific epithet in recognition of Rohini Balakrishnan whose research involves bioacoustics, animal behavior, ecology, and systematics. Her list of publications includes several that focus on or include tree crickets. The common name, Cri-Cri tree cricket, is named for Cri-Cri: El Grillito Cantor (Cri-Cri: The Little Singing Cricket), which was a character created by Francisco Gabilondo Soler, a Mexican composer and performer of children’s songs. Additionally, the sound this tree cricket makes is written as “cri, cri...” in Spanish. Holotype measurements.—Body length 13.0 mm; tegminal length 13.0, tegminal width 6.0; pronotal length 2.0, distal pronotal width 2.0; hind femur length 7.0; cerci 5.0; stridulatory file length 1.8. Right tegminal stridulatory teeth total 46. Description.—Face pale; head with area of pale orange (Figs 4, 5). Scape translucent orange, pedicel translucent whitish (Fig. 6), and remainder of antennomeres translucent whitish. Ventral face of pedicel and scape each with one ovoid or rounded black mark on white field (Figs 3, 19). Eye color pale cream to violet. Palpi pale golden orange with whitish tips. Pronotum light green. Tympa- nal membrane on fore tibiae whitish. Wing color greenish. Ven- tral abdomen whitish with blotches of light green (Fig. 8). Tarsi, tibiae, and femora translucent pale green; some individuals with blackish thin line down inner femora. Cerci straight and translu- cent pale green. Males.—Hind wings and cerci extend beyond distal edge of teg- mina (Fig. 1). Tegmina with veins as in Fig. 2. Body length 13.0- 13.5 mm; tegminal length 13.0-13.5, tegminal width 5.8-6.0; pronotal length 2.0, distal pronotal width 2.0-2.2; hind femur length 7.0-7.6; cerci 5.0; stridulatory file length 1.8-2.0. Right tegminal stridulatory teeth total 46-48. Metanotal gland with triangular opening, and bristles running horizontally across the top of the opening (Fig. 7). Subgenital plate tapers to a rounded tip (Fig. 8). Copulatory blades with rounded medial sides and a notch separating them slightly narrower than width of a blade. Each blade with a small hook at distal tip (Figs 9, 10). JOURNAL OF ORTHOPTERA RESEARCH 2021, 30(1) N. COLLINS, ILM. CORONADO-GONZALEZ, A.Y. ROCHA-SANCHEZ, B. GOVAERTS AND W. HERSHBERGER 9 1 Figs 1-10. Oecanthus rohiniae sp. nov., male. 1. Habitus; 2. Singing male showing the tegmina in raised position; 3. Head in frontal view showing the antennal marks; 4. Rounded patch of color on head; 5. Notched patch of color on head; 6. Antennal base, lateral view; 7. Metanotal gland; 8. Subgenital plate in ventral view; 9. Internal genitalia in ventral view; 10. Internal genitalia in dorsal view. JOURNAL OF ORTHOPTERA RESEARCH 2021, 30(1) 10 N. COLLINS, ILM. CORONADO-GONZALEZ, A.Y. ROCHA-SANCHEZ, B. GOVAERTS AND W. HERSHBERGER Figs 11-13. Oecanthus rohiniae sp. nov., female; 11. Habitus, female eating on Croton cilatoglandulifer Ort; 12. Cerci; 13. Ovipositor. Morphological diagnosis.—Oecanthus rohiniae sp. nov. can be dis- tinguished from O. rileyi by differences in antennal markings and from O. fultoni by differences in the distal hooks of the copulatory blades of the male genitalia. The antennal markings of O. rohin- ide sp. nov. are centered and fairly equal in size (Figs 3, 20). The antennal marking on the pedicel of O. rileyi is positioned at the top of the segment, and is approximately one-half the size of the marking on the scape (Fig. 22). A drawing in Walker and Gurney (1960) of male genitalia shows that the distal ends of the copula- tory blades of O. fultoni appear rounded with sharply pointed me- dially opposing hooks (Fig. 27). The distal ends of the copulatory blades of O. rohiniae sp. nov. are more blunted, and the tips of the hooks are less pointed (Fig. 23). A second drawing in Walker and Gurney (1960) shows an undetermined rileyi species group tree cricket from Tamaulipas, Mexico (Fig. 24) with hook position similar in appearance to O. rohiniae sp. nov. Photos of the lateral view of the blades of O. rohiniae sp. nov. (Fig. 25) and O. fultoni (Fig. 28) highlight the hook tip differences. Female description.—(Figs 11-13) Latticed vein pattern on translu- cent greenish wings. Body length 11.5 mm; pronotal length 2.0, distal pronotal width 2.0; hind femur length 7.0; cerci 4.5; ovi- positor length 3.5. The length of the hindwings is variable. The tip of the ovipositor does not extend beyond the tips of the cerci. JOURNAL OF ORTHOPTERA RESEARCH 2021, 30(1) N. COLLINS, I.M. CORONADO-GONZALEZ, A.Y. ROCHA-SANCHEZ, B. GOVAERTS AND W. HERSHBERGER 11 Figs 14, 15. Characters of O. rohiniae sp. nov. nymphs: Even rows of white rounded markings on the abdomen, black speckles on the hind femora, and black rings on the antennal filaments. Nymphs.—(Figs 14, 15) Straight rows of white rounded marks on the abdomen, black speckles on the hind femora, and evenly spaced black rings on the antennal filaments. Nymphs of various instar stages, as well as adults, were encountered year round. Distribution and habitat.—Cri-Cri tree crickets have only been collected in the type locality in the biogeographic province of the Trans-Mexican Volcanic Belt, in the State of Querétaro, located in the Central-South part of Mexico. The vegetation was categorized by dry shrubland with cacti (crassifolia), grassland (mattoral), reinvading natural vegetation on disturbed land (ruderal), and introduced plants. A total of 33 plant species were able to be identified in the type locality (Calder6n de Rzedowski and Rzedowski 2001, Martinez-Sandoval 2017). Adults and nymphs of this new species of tree cricket were observed on 14 of these plant species and were witnessed feeding on eight plant species (native plants: Asclepias curassavica L., Croton cilatoglandulifer Ott., Justicia candicans (Nees) L.D., Lantana camara L., Lantana hirta Graham, Colubrina triflora Brogn Ex Sweet (also oviposition) and introduced plants: Calendula officinalis L., Cnidoscolus multilobus (Pax) I. M. Johnst, Ruta graveolens L., and Thunbergia alata Bojer Ex Sims). An ovipositing female as well as nymphs were found on Colubrina triflora Brogn. Ex Sweet, a native plant. Nymphs were found on three native plants: Lantana hirta Graham, L. camara L, and C. cilatoglandulifer Ort. Climate and light intensity.—National Weather Commission (NWC 2020) data for 2009-2019 showed the coldest months as Decem- ber and January (lowest 4.0°C) and the warmest months as April and May (highest 33.2°C). The driest months tend to be Novem- ber through March (lowest 0.0 mm) and the wettest months tend to be June through September (highest 207.0 mm). Males sing just before or after sunset with light measurements of 5 W/m? and temperatures as low as 11.0°C. Acoustics, chirp rates, frequencies, and slopes. Recordings were made in the field and in captivity for O. rohiniae sp. nov. A sample re- cording can be heard in Suppl. material 3: WAV, and a stridulating male can be viewed in Suppl. material 4: MPG. After plotting the data of temperature vs chirps per minute and carrier frequency vs temperature, linear regression lines were calculated for O. rohiniae sp. nov., O. fultoni, and O. rileyi. The linear regression for tempera- JOURNAL OF ORTHOPTERA RESEARCH 2021, 30(1) 12 ture vs chirps per minute of O. rohiniae sp. nov. was calculated to be y=7.0418x — 5.3551, and at 25.0°C the chirps per minute rate was 171 (Fig. 17). The linear regression for carrier frequency (kHz) vs temperature (degrees celsius) of O. rohiniae sp. nov. was calculated to be y=0.0685x + 0.09002, and at 25.0°C the carrier frequency was 2.61 kHz (Fig. 18). The chirps per minute rate vs temperature response of O. rohiniae sp. nov. is distinctly different from O. rileyi. The slopes of both O. rohiniae sp. nov. and O. fultoni were further examined using a t-test analysis. This analysis resulted in a t-value of t(47)=3.08 with a probability value of p=0.0035, clearly indi- cating that the slopes of the chirps per minute vs temperature re- sponse for both species are significantly different at the 99% level. Chirp pulse pattern comparisons and diagnosis.—Visual inspection of song oscillograms revealed that O. rohiniae sp. nov. has chirps with grouped pulses. The chirp pulse grouping patterns of O. ro- hiniae sp. nov. are 2-2, 2-3, 2-3-2 or 2-3-3 (Fig. 19). Of the 601 individual chirps examined, 76.9% were 2-3 or 2-3-2 patterns. The predominant patterns for O. fultoni were 2-3 or 2-3-3. We found “Me Fig. 16. Oscillograms of the calling song of O. rohiniae sp. nov. at 17.0°C. A. Two chirps; B. Three seconds of chirping; C. 15 seconds of chirping. Wns oe Ww. Ve Or hw w N. COLLINS, ILM. CORONADO-GONZALEZ, A.Y. ROCHA-SANCHEZ, B. GOVAERTS AND W. HERSHBERGER 250 200 ie = et eral = 150 ae i = wey s i m a bel 2 a eae 2 100 2a 1 = ° es cd pak. = ft ede ls Q FE ak 50 0 5 10 15 20 25 30 35 Temperature (°C) = O. fultoni soo W = 9,2366x - 63.931 R 942 a O. rileyi ---y=4.07x + 4.9087 R? = 0.936 © O. rohiniae sp. nov. --- y=7.0418x- 5.3551 2 Fig. 17. Change in chirps per minute with temperature of O. rohin- iae sp. nov., O. fultoni, and O. rileyi. Data for O. fultoni and O. rileyi recordings in Suppl. material 2: source recordings. 3.5 = - 5 e = N - | m ge — 2.5 . oe all 1. a ee et F] * ee: ae 2 . ec Kee > oe % 2 e aoa ee =. 8 ft s he ad CT] te . 2 ofe--* 22 ge - “xe a e wy a o ie a « 15 1 5 10 15 20 25 30 35 Temperature (°C) © O. rohiniae sp. nov. = O. fultoni a O, rileyi == y= 0.0685x + 0.9002 ann Y= 0.0782x +0.6527 = + ¥=0.0679x + 0,7678 R= 0.84 R?= 0.7598 R?=0,9555 Fig. 18. Change in carrier frequency with temperature of O. rohini- ae sp. nov., O. fultoni, and O. rileyi. Data for O. fultoni and O. rileyi recordings in Suppl. material 2: source recordings. » a m oo ie ho hd bh 7 14.6 “a4060°¢C*