Oecanthus rohiniae Collins & Coronado-Gonzalez, 2021

Collins, Nancy, Coronado-Gonzalez, Isabel Margarita, Rocha-Sanchez, Aurora Y., Govaerts, Bruno & Hershberger, Wilbur, 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), pp. 7-16 : 7-11

publication ID	https://dx.doi.org/10.3897/jor.30.50039
publication LSID	lsid:zoobank.org:pub:453DAF66-5CC1-4CC9-870E-2EDD98BFDE52
persistent identifier	https://treatment.plazi.org/id/EE607E6F-B950-4FDF-BCA0-742177F85FD4
taxon LSID	lsid:zoobank.org:act:EE607E6F-B950-4FDF-BCA0-742177F85FD4
treatment provided by	Journal of Orthoptera Research by Pensoft
scientific name	Oecanthus rohiniae Collins & Coronado-Gonzalez
status	sp. nov.

Treatment

Oecanthus rohiniae Collins & Coronado-Gonzalez View in CoL sp. nov.

Material examined. -

Holotype: MEXICO • ♂; Querétaro, Corregidora ; 2130 MASL; 30.xi.2019; 20°52'20"N, 100°38'80"W; I. Coronado leg.; deposited Universidad Nacional Autónoma de México (IB-UNAM) . Paratypes: MEXICO • 2 ♂, 3 ♀; same locality as holotype ; 2 ♂, 2 ♀ deposited Tecnologico Nacional de Mexico-Instituto Tecnologico de Ciudad Victoria (TecNM-ITCV) ; 1♀ 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 View Figures 1–10 , 5 View Figures 1–10 ). Scape translucent orange, pedicel translucent whitish (Fig. 6 View Figures 1–10 ), 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 View Figures 1–10 , 19 View Figure 19 ). Eye color pale cream to violet. Palpi pale golden orange with whitish tips. Pronotum light green. Tympanal membrane on fore tibiae whitish. Wing color greenish. Ventral abdomen whitish with blotches of light green (Fig. 8 View Figures 1–10 ). Tarsi, tibiae, and femora translucent pale green; some individuals with blackish thin line down inner femora. Cerci straight and translucent pale green.

Males. -

Hind wings and cerci extend beyond distal edge of tegmina (Fig. 1 View Figures 1–10 ). Tegmina with veins as in Fig. 2 View Figures 1–10 . 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 View Figures 1–10 ). Subgenital plate tapers to a rounded tip (Fig. 8 View Figures 1–10 ). 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 View Figures 1–10 , 10 View Figures 1–10 ).

Morphological diagnosis. -

Oecanthus rohiniae sp. nov. can be distinguished from O. Oecanthus 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. rohiniae sp. nov. are centered and fairly equal in size (Figs 3 View Figures 1–10 , 20 View Figures 20–22 ). 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 View Figures 20–22 ). A drawing in Walker and Gurney (1960) of male genitalia shows that the distal ends of the copulatory blades of O. fultoni appear rounded with sharply pointed medially opposing hooks (Fig. 27 View Figures 23–28 ). 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 View Figures 23–28 ). A second drawing in Walker and Gurney (1960) shows an undetermined Oecanthus rileyi species group tree cricket from Tamaulipas, Mexico (Fig. 24 View Figures 23–28 ) 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 View Figures 23–28 ) and O. fultoni (Fig. 28 View Figures 23–28 ) highlight the hook tip differences.

Female description. -

(Figs 11-13 View Figures 11–13 ) Latticed vein pattern on translucent greenish wings. Body length 11.5 mm; pronotal length 2.0, distal pronotal width 2.0; hind femur length 7.0; cerci 4.5; ovipositor length 3.5. The length of the hindwings is variable. The tip of the ovipositor does not extend beyond the tips of the cerci.

Nymphs. -

(Figs 14 View Figures 14, 15 , 15 View Figures 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 ( Calderón de Rzedowski and Rzedowski 2001, Martínez-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 Ort., 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. Lantana camara L, and C. Croton cilatoglandulifer Ort.

Climate and light intensity. -

National Weather Commission ( NWC 2020) data for 2009-2019 showed the coldest months as December and January (lowest 4.0°C) and the warmest months as April and May (highest 33.2°C). The driest months tend to be November 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/m2 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 recording 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 ture vs chirps per minute of O. rohiniae sp. nov. was calculated to be y=7.0418 × - 5.3551, and at 25.0°C the chirps per minute rate was 171 (Fig. 17 View Figure 17 ). The linear regression for carrier frequency (kHz) vs temperature (degrees celsius) of O. rohiniae sp. nov. was calculated to be y=0.0685 × + 0.09002, and at 25.0°C the carrier frequency was 2.61 kHz (Fig. 18 View Figure 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 indicating that the slopes of the chirps per minute vs temperature response 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. rohiniae sp. nov. are 2-2, 2-3, 2-3-2 or 2-3-3 (Fig. 19 View Figure 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 two instances of apparent aborted chirps with a single 2-pulse grouping, but we found no recordings of a singing O. fultoni with a 2-3-2 pattern. Table 1 View Table 1 shows the percentage of occurrence for chirp pulse patterns for O. rohiniae sp. nov., O. fultoni , and O. rileyi . Since O. rohiniae sp. nov. has a total of 11 or less pulses per chirp, both O. alexanderi and O. allardi can be ruled out as their chirps consist of 17-23 or 29-35 pulses, respectively ( Walker and Collins 2010). Oecanthus mhatreae does not have grouping of pulses in each chirp ( Collins et al. 2019).

Other species comparisons. -

The known members of the nigricornis, niveus, and varicornis species groups can be ruled out with non-matching song types, tegminal widths, antennal markings, or antennal coloring. Other western hemisphere species of Oecanthus can be ruled out for non-matching characters as in Table 2 View Table 2 .

Morphological comparisons. -

Since both O. rohiniae sp. nov. and O. fultoni are members of the Oecanthus rileyi species group, it is not unexpected that no profound differences were evident in the following characters: coloring, antennal markings, metanotal gland, number of stridulatory teeth, tegmen venation, and subgenital plates. The pedicel of O. rohiniae sp. nov. has a centered black mark more than one half the size of that on the scape (Fig. 20 View Figures 20–22 ), which is also found on O. fultoni (Fig. 21 View Figures 20–22 ) but not on O. rileyi (Fig. 22 View Figures 20–22 ). These markings can be either round or ovoid. The copulatory blades of O. rohiniae sp. nov. have distal hooks that appear somewhat blunted and are positioned at a slight angle (Fig. 23 View Figures 23–28 ), while those of O. fultoni have hooks that are more sharply pointed with tips that reach further midline (Fig. 26 View Figures 23–28 ). These differences can be compared to drawings in Walker and Gurney (1960) comparing male genitalia of a rileyi species group tree cricket from Tamaulipas, Mexico (Fig. 24 View Figures 23–28 ) with a snowy tree cricket from Ohio (Fig. 27 View Figures 23–28 ). While we cannot proclaim that the drawing of the Tamaulipas tree cricket in Fig. 24 View Figures 23–28 is O. rohiniae sp. nov., the differences in the two drawings do affirm that more than one species of the Oecanthus rileyi group exists in Mexico. The difference in the appearance of the hooks on fresh specimens can be seen from a lateral view of the blades, as in Figs 25 View Figures 23–28 , 28 View Figures 23–28 .