Orthoptera of North Carolina
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View Gryllidae Members: NC Records

Anaxipha tinnula Walker & Funk, 2014 - Tidewater Trig


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Taxonomy
Family: Gryllidae Subfamily: Trigonidiinae Tribe: TrigonidiiniSynonym: Anaxipha n. sp. E; Anaxipha scia (sensu Fulton)
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. Tinnula belongs to the Exigua Species Group, which also includes exigua, tinnulacita, thomasi, and tinnulenta in North Carolina (Walker and Funk, 2014).
Species Status: Fulton (1956) identified this species as Anaxipha scia (Hebard), but it was later recognized as a distinct species by Walker and Funk (2014).
Identification
Field Guide Descriptions: Online Photographs: SINA, Google ImagesTechnical Description, Adults/Nymphs: Walker and Funk (2014)SINA 610a.htm                                                                                  
Comments: A very small, brown Trig. Like other members of the exigua group, it possess a stripe on the lateral face of the femur, although it is often pale or obsolescent in this species (Walker and Funk, 2014). Structural features -- particularly the number of pegs on the stridulatory file -- must be examined to identify this species; the song and habitat associations are also distinctive.
Total Length [body plus wings; excludes ovipositor]: 6.4-6.7 mm, males; 7.0 mm, females (Walker and Funk, 2014)
Structural Features: Stridulatory file with about 200 teeth (range 184-217). Length of ovipositor 1.8-2.0 mm. Ratio of length of hind femur to ovipositor 2.4-2.8 Walker and Funk, 2014). Long-winged forms have been observed (Fulton, 1956) but appear to be rare (Walker and Funk, 2014).
Singing Behavior: According to Walker and Funk (2014), the song of tinnula is a slow, continuous tinkle, with pulse rate of about 8 pulses per second at 77 degrees F (= 25 C), with the dominant frequency about 6.5 kHz. Fulton (1956) described the song of tinnula (which he called scia) as bell-like and similar to both tinnulenta and tinnulacita (which he regarded as forms of exigua). At temperatures between 60 and 5 degrees F, Fulton observed the pulse rate of tinnula to be 4-5 pulses per second, compared to 3-4 for tinnulenta and 7-9 for tinnulacita. Fulton also noted that Allonemobius tinnulus has a slow tinkling song very similar to that of tinnula but that it occurs in very different habitats (dry upland woods).
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: Appears to be restricted to marsh grasses, including those of saltwater marshes (Carolina Beach) and fresh-to-brackish marshes (New Bern and Swanquarter) (Fulton, 1956)
Diet: Associated with tall grasses, sedges, and rushes but its exact diet is unrecorded
Observation Methods: Most easily detected by its song. Fulton (1956) noted that tinnula, like tinnulenta and tinnulacita, sing most vigorously in the morning and much less on cool nights.
Abundance/Frequency: Fulton (1956) collected large numbers on at least a couple of occasions: 34 at New Bern and 40 at Carolina Beach
Adult Phenology: Adults have been collected in August and September in North Carolina (Fulton, 1956)
Status in North Carolina
Natural Heritage Program Status:
Natural Heritage Program Ranks: [GNR] [S3S4]
State Protection: Has no legal protection, although permits are required to collect it on state parks and other public lands
Comments: All of our records for this species are historic, although it is highly likely to still occur in our coastal marshes. It appears to be highly specialized on tall marsh graminoids and is likely to be vulnerable to coastal development. Since it apparently can use a variety of marsh habitat types, however, it may be relatively immune to the effects of sea level rise and may actually benefit from swamp or peatland conversion to marshes due to salt water intrusion. Nonetheless, surveys should be conducted to determine its current distribution, habitat and dietary associations to assess its current status within the state.