Orthoptera of North Carolina
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View Gryllidae Members: NC Records

Anaxipha thomasi Walker & Funk, 2014 - Thomas's Trig


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Taxonomy
Family: Gryllidae Subfamily: Trigonidiinae Tribe: TrigonidiiniSynonym: Anaxipha n. sp. D
Comments: One of thirteen species in this genus that occur in North America north of Mexico (SINA, 2017); nine have been recorded in North Carolina. Thomasi belongs to the Exigua Species Group, which also includes exigua, tinnula, tinnulacita, and tinnulenta in North Carolina (Walker and Funk, 2014).
Identification
Field Guide Descriptions: Online Photographs: SINA, Google ImagesTechnical Description, Adults/Nymphs: Walker and Funk (2014)SINA 630a.htm                                                                                  
Comments: A very small, brown Trig. Like other members of the Exigua group, it possess a broad dark stripe on the lateral face of the femur (Walker and Funk, 2014). Structural features -- particularly the number of pegs on the stridulatory file -- must be examined to identify this species; the song is distinctive.
Total Length [body plus wings; excludes ovipositor]: 5.5-5.9 mm, males; 6.1-7.1, females (Walker and Funk, 2014)
Structural Features: "Stridulatory file with about 150 teeth (range 139-162). Length of ovipositor <2.2 mm" (see Walker and Funk, 2014 for additional structural characteristics). No macropterous individuals have been observed but the sample size is still fairly small.
Singing Behavior: Song is a continuous trill at ~21 pulses per sec at 7.8 kHz (at 25°C) (Walker and Funk, 2014). The pulse rate is slower than exigua and the dominant frequency is higher.
Recording playback at normal speed.

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Nymphal Stages and Development: Apparently undescribed but unlikely to be distinguishable, particularly from other members of the Exigua Species Groups
Distribution in North Carolina
County Map: Clicking on a county returns the records for the species in that county.
Adult Dates:
 High Mountains (HM) ≥ 4,000 ft.
 Low Mountains (LM) < 4,000 ft.
 Piedmont (Pd)
 Coastal Plain (CP)

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Habitats and Life History
Habitats: This species appears to be particularly tied to pine forests (Walker and Funk, 2014) and our records come from stands dominated by Shortleaf Pine with some Scrub Pine also present.
Diet: Apparently unrecorded; possibly omnivorous
Observation Methods: Singing males are most easily detected but they may also be captured using sweep netting
Abundance/Frequency: We currently have too few records for this species to estimate either its frequency of occurrence or abundance
Adult Phenology: Walker and Funk (2014) report that this species is univoltine, appearing in late summer and persisting into the fall. Our records are all from mid-September, consistent with this phenology.
See also Habitat Account for General Dry-Xeric Pine Forests and Woodlands
Status in North Carolina
Natural Heritage Program Status: [W3]
Natural Heritage Program Ranks: [GNR] [SU]
State Protection: Has no legal protection, although permits are required to collect it on state parks and other public lands
Comments: This recently described species is still too poorly known across its range to estimate either its global or state conservation status. Its occurrence in stands of upland pine forests suggests, however, that it may be fairly secure. However, that remains to be confirmed.

Image Gallery for Anaxipha thomasi - Thomas's Trig

Recorded by: Steve Hall
Durham Co.
Comment: 24 pulses per second at about 80 F; singing along the edge of a floodplain where pines were common in the forest and saplings occurred along the trail
Recorded by: Steve Hall
Iredell Co.
Comment: 20 pulses/sec; 8:50, 73 F
Recorded by: Steve Hall
Orange Co.
Comment: 23 pulses per second @ 8.2 kHz. Temperature at noon was about 78 degrees F (= 25.6 C); calling from near the ground -- possibly on low blueberries -- in a pine stand