Research Article |
Corresponding author: Nancy Collins ( oecanthinae@gmail.com ) Academic editor: Klaus-Gerhard Heller
© 2021 Nancy Collins, Carlos Gerardo Velazco-Macias.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Collins N, Velazco-Macias CG (2021) Neoxabea mexicana sp. nov. (Gryllidae: Oecanthinae): A new species from Mexico and a key for Neoxabea in North and Central America. Journal of Orthoptera Research 30(2): 99-106. https://doi.org/10.3897/jor.30.62000
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A new species of tree cricket, Neoxabea mexicana sp. nov., is described from northeast Mexico. Although it has morphological similarities to two other species found in Mexico, there are distinguishing characters, such as a well-developed tubercle on the pedicel, black markings on the maxillary palpi, one of the two pairs of spots on the female wings positioned at the base of the wings, stridulatory teeth count, and the pulse rate of the male calling song. The calling song description and pre-singing stuttering frequencies are provided. Character comparisons that rule out other species in the genus are presented. The common name given to this new species is Mexican tree cricket. Sound recordings and video are available online. We also make some clarification of the status of Neoxabea formosa (Walker, 1869), described as Oecanthus formosus, and present a key of Neoxabea in North and Central America.
Acoustics, key, Nuevo Leon, Orthoptera, pedicel tubercle
A photograph posted in October 2018 (Fig.
The morphology and song data of N. bipunctata are well documented and thus easily compared to this new species. The lack of data for N. formosa, along with its complicated history, presented challenges. In his description of Oecanthus formosus Walker, 1869, a female specimen from the collection of M. Salle was designated as the holotype (
In November 2020, after requesting confirmation from NHMUK that the type specimen of Oecanthus formosus was missing, as cited in the OSF website (
Thirteen specimens from Mexico and Brownsville, Texas, were examined by T. Walker in four major collections (
A photograph taken by NC in September 2019 (Fig.
This paper describes a new species of Neoxabea that has a stridulatory teeth count that falls within the range of some of the male specimens labeled as N. formosa that T. Walker examined in 1966. The original species of N. formosa remains intact, with the only known specimen being the holotype, a female, at the NHMUK in South Kensington, and which was collected at the volcano Orizaba in Veracruz, Mexico (Fig.
Collection methods.—Individuals were found on an outdoor illuminated ceiling and walls.
Type verification.—Keys from
Song recordings and analyses.—Songs of an actively roaming captive male were recorded using a Huawei P30 Pro cellphone held as close to the singing tree cricket as possible. The cellphone was tested for calibration by recording a file from SINA and comparing the pulse rate and frequency to the original file. Raven Lite 2.0 was used to prepare waveforms to count pulse rates, and spectrograms were used to determine carrier frequency.
Habitat.—Individuals were found on the private property of CGV-M in Guadalupe, Monterrey, Nuevo Leon, in northeast Mexico. Native vegetation on the property includes Tecoma stans (L.) Juss. ex Kunth; Senna alata (L.) Roxb.; Asclepias curassivica L.; Lantana camara L.; Poliomintha bustamanta B. L. Turner; Croton ciliatoglandulifer Ortega; Ruellia simplex C. Wright; Merremia dissecta (Jacq.) Hallier f. (
Guadalupe sits at the base of Cerro de La Silla, and the private property sits approximately 800 meters from the start of vegetation of the mountain. Species of vegetation that predominate on the mountain are Vachellia rigidula (Benth.) Seigler & Ebinger; Vachellia farnesiana (L.) Wight & Arn.; Cordia boissieri A. DC.; and Opuntia spp. At higher altitudes, the following are more frequent species: Havardia pallens (Benth.) Britton & Rose; Helietta parvifolia (A. Gray) Benth.; Caesalpinia mexicana (A. Gray, 1861) E. Gagnon & G. P. Lewis, 2016; Leucaena pulverulenta (Schltdl.) Benth; and a naturalized tree from southern Mexico—Leucaena leucocephala (Lam.) de Wit. In the highest zone, Quercus fusiformis Small and Q. canbyi Trel. occur (
Climate.—Temperatures of the spots where tree crickets were singing were measured using a Steren thermometer, Model TER-150, with a range of -10 to 50°C.
Preservation of specimens .—Specimens were preserved in 70% ethyl alcohol.
Morphological measurements.—Measurements were made after the specimens were euthanized by freezing or by immersion in 70% ethyl alcohol. Total body length refers to the midline length from the tip of the labrum to the apex of the subgenital plate, not including antennae, tegmina, limbs, or cerci. Tegminal 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. Female ovipositors were measured from the base at the distal abdomen to the tip. Photographs and measurements of the ovipositor, cerci, and metanotal gland, as well as counts of the stridulatory teeth, were made with the aid of an AmScope Stereoscope, magnification WF10× to 2× to 4× (photographs made using a Huawei P30PRO cellphone camera with a Leica Vario-Summilux-H1.6-3.4/16-125 ASPH lens). Comparison photographs of N. bipunctata, N. cerrojesusensis, and N. ottei were made with a Canon PowerShot S5 IS.
Male genitalia.—The male genitalia complex was extracted and photographed using a Huawei P30PRO cellphone camera with a Leica Vario-Summilux-H1.6-3.4/16-125 ASPH lens. Copulatory blades (
Holotype ♂ (Fig.
Face, head, and pronotum brown. Pedicel and scape brown, each with one protruding tubercle (Fig.
Located October 2020 on private property in Bosques del Rey, Guadalupe, Nuevo Leon, Mexico. 2 ♂ and 1 ♀ deposited at Universidad Nacional Autónoma de Mexico (UNAM), one ♂ of these designated as the holotype for this species.
The genus Neoxabea was determined as the Nuevo Leon specimens lacked spines on the hind tibiae (Figs
Total body length 17.0 mm, tegminal length 12.5, tegminal width 5.5, pronotal length 3.5, distal pronotal width 3.0, proximal pronotal width 2.2, hind femur length 9.0, cerci 2.25. Stridulatory file length 2.0. Right tegminal stridulatory teeth total 53.
The metanotal gland, color of the ventral abdomen, cerci, distal abdominal terga projections, ovipositor, and copulatory blades are presented in Figs
One female was not euthanized and only partially measured. Latticed vein pattern on wings with a single large dark pair of spots at lateral edges mid-wing (Figs
The maxillary palpi of N. mexicana sp. nov. have a longitudinal black line (Fig.
Calling song recordings were made in captivity by CGV-M (Suppl. material
The tone of the trilling portion of the song of N. mexicana sp. nov. is more musical and flute-like than the buzzy sound of the faster song of N. bipunctata. Both species have a pre-trilling stuttering, but the stuttering of N. mexicana sp. nov. is longer in duration, more consistently present, and was found to be more flute-like in tone even at moderate temperature (22.7°C). Neoxabea mexicana sp. nov. has a 200 Hz difference between the frequency of the stuttering and the song trilling, while the frequency of N. bipunctata remains constant.
1 | Females | 2 |
1’ | Males (male of N. formosa unknown) | 6 |
2(1) | Two pairs of prominent dark spots on lateral edges of female wings at rest; located in mid portion (Fig. |
3 |
2’ | Two pairs of prominent dark spots on lateral edges of female wings at rest; with one of the pairs located at base (Fig. |
5 |
3(2) | Ruddy line on each segment of the maxillary palpi; slight dimple on pedicel (Fig. |
♀ N. bipunctata |
3’ | Dark brown or black line on each segment of the maxillary palpi | 4 |
4(3’) | Dimple on pedicel unknown (only scape present on holotype) | ♀ N. formosa |
4’ | Moderate dimple on pedicel (Fig. |
♀ N. ottei |
5(2’) | Moderate dimple on pedicel (Fig. |
♀ N. cerrojesusensis |
5’ | Prominent tubercle on pedicel (Fig. |
♀ N. mexicana |
6(1’) | Large amount of dark brown staining on male tegmina; black line on each segment of the maxilary palpi; prominent tubercle on pedicel; song with < 40 pulses per second at 26.0°C; stridulatory teeth count > 50 (Fig. |
♂ N. mexicana |
6’ | No or minimal male tegmina staining; dimple on pedicel; stridulatory teeth count < 30 | 7 |
7(6’) | Ruddy line on each segment of the maxillary palpi; pedicel with slight dimple; song with > 100 pulses per second at 26.0°C (Fig. |
♂ N. bipunctata |
7’ | Dark brown or black lines on each segment of the maxillary palpi; moderate dimple on pedicel; song with >70 pulses per second at 26.0°C | 8 |
8(7’) | Tegmina dark staining pattern generally a full X; resting tegminal width > 4.5 mm (Fig. |
♂ N. ottei |
8’ | Tegmina dark staining pattern generally the top half of an X; resting tegminal width < 4.5 mm (Fig. |
♂ N. cerrojesusensis |
Neoxabea species comparisons
.—The 13 described species of Neoxabea can be ruled out as N. mexicana sp. nov. with non-matching characters, as in Table
Non-matching characters of 13 described species of Neoxabea when compared to N. mexicana sp. nov.
Neoxabea species | Characters not matching N. mexicana sp. nov. | Sources |
---|---|---|
N. ottei (Collins & van den Berghe, 2014) | < 25 stridulatory teeth; females w/ 4 centrally located wing spots |
|
N. astales (Walker, 1967) | < 30 stridulatory teeth; no abdomen terga projections | T. |
N. bipunctata (DeGeer, 1773) | < 30 stridulatory teeth | T. |
N. cerrojesusensis (Collins & van den Berghe, 2014) | < 30 stridulatory teeth; male tegmina with minimal staining |
|
N. obscurifrons (Bruner, 1916) | < 30 stridulatory teeth; drab coloring | T. |
N. femorata (Walker, 1967) | < 40 stridulatory teeth; striped hind femora | T. |
N. trinodosa (Hebard, 1928) | 75–80 stridulatory teeth | T. |
N. brevipes (Rehn, 1913) | Spotting on limbs; song > 54 pps at 19°C | T. |
N. enodis (Walker, 1967) | Bold cephalic pattern; no abd terga projections | T. |
N. lepta (Walker, 1967) | Long, thin, straight cerci; no abd terga projections | T. |
N. meridionalis (Bruner, 1916) | Distinct tegmina staining; no abd terga projections | T. |
N. formosa (Walker, 1869) | Females with four centrally located spots on wings | F. |
N. quadrula (Walker, 1967) | Cerci with large swelling; 35 stridulatory teeth | T. |
Morphology of N. mexicana sp. nov. 8A. Metanotal gland; 8B. Labeled metanotal gland; 9. Ventral abdomen color and subgenital plate on live male; 10. All eight projections on dorsal abdominal terga of male; 11. Dorsal view of male cerci; 12. Ventral view of female ovipositor; 13A. Ventral view of copulatory blades (main lobe of pseudepiphallus) of holotype male; 13B. Dorsal view; 13C. Lateral view.
Waveforms of the calling song of N. mexicana sp. nov. at 26.6°C (after applying 2 kHz high pass filtering); A. Six bursts of singing in 50 sec.; B. One burst of singing with warm up stuttering before next burst of singing; C. One second of warm up stuttering showing a total of 17 pulses (click sounds); D. One second of singing (36 pulses per second).
Images of adult wing patterns, palpi markings, and pedicel tubercles for species in the Neoxabea key. A. mexicana sp. nov. ♀; B. cerrojesusensis ♀; C. bipunctata ♀; D. ottei ♀; E. formosa ♀; F. mexicana sp. nov. ♂; G. cerrojesusensis ♂; H. bipunctata ♂; I. ottei ♂; J. bipunctata; K. mexicana sp. nov.; L. formosa; M. cerrojesusensis; N. ottei; O. mexicana sp. nov.; P. cerrojesusensis; Q. ottei; R. bipunctata.
This investigation revealed the following characters for Neoxabea mexicana sp. nov.: well-developed tubercles on the pedicel as well as the scape; a black line on all segments of the maxillary palpi; a large amount of dark staining on the male tegmina, and one pair of dark spots on the wings of females located at the base. These characters, along with the calling song rate and stridulatory teeth count, are distinctly different from those in N. bipunctata, which is also reported from Mexico. While the warm-up stuttering and the singing phase of N. bipunctata remain at a consistent frequency, the song of N. mexicana sp. nov. consistently shows a rise from the stuttering phase to the singing phase of up to 200 kHz.
In this paper, we focus on comparisons to N. bipunctata, since that species is well studied and documented as occurring in Mexico. Comparisons to other species of Neoxabea in Table
Our recommendation for male specimens currently labeled as N. formosa in collections is to treat them as either N. formosa or N. mexicana sp. nov. until a living male can be verified as N. formosa. Female specimens labeled as N. formosa with two pairs of centrally located spots on the wings cannot currently be distinguished from N. ottei, but the intensity of the line on the maxillary palpi can be used for differentiating between N. bipunctata and N. formosa.
We thank the California Academy of Sciences and National Geographic Society for maintaining the website iNaturalist.org along with CONABIO for the Mexican site Naturalista.mx, which allows scientists and the public from around the world to post photographs and sound recordings of insects. We thank Klaus-Gerhard Heller, Sigfrid Ingrisch, Thomas J. Walker, Edison Zefa and Tony Robillard for their review of this paper and valuable recommendations. José Gerardo Velazco Castañon helped in locating the specimens for collection and analysis. Klaus-Gerhard Heller helped locate the specimen in the Natural History Museum. Ben Price, Natural History Museum, South Kensington, UK, provided images of the female specimen labeled as the holotype for Neoxabea formosa. Teresa Yawn, University of Florida, provided photos of specimens labeled as N. formosa in the Florida State Collection of Arthropods (FSCA). Judith Marshall, Curator Emeritus, provided the history of the NHMUK. Carl Strang and James Trager offered critiques of the key. The Orthopterists’ Society provided funding for the publication of this paper.
Data type: Movie (mov. file)
Explanation note: Mating pair of N. mexicana sp. nov..
Data type: Image (jpg. file)
Explanation note: Structures of N. mexicana sp. nov.: A. Holotype right wing stridulatory file with teeth; B. Female tympanal membrane; C. Male tympanal membrane with front limb claw; D. Spermatophore; F. Ovipositor.
Data type: WAV file
Explanation note: Recording of captive male.
Data type: WAV file
Explanation note: Recording of captive male.
Data type: Excel spreadsheet
Explanation note: Graph of recording data for four species of Neoxabea.
Data type: Image (jpg. file)
Explanation note: Photographs of the female holotype for N. formosa – taken at the Natural History Museum in the UK.