Orthoptera of North Carolina
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View Gryllidae Members: NC Records

Pictonemobius ambitiosus complex - No Common Name


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Taxonomy
Family: Gryllidae Subfamily: Nemobiinae Tribe: Pteronemobiini
Comments: One of four species in this genus, all of which are confined to southeastern North America (Cigliano et al., 2017). While one member of this genus has been recorded in North Carolina, it is not clear which species it represents (Gross et al., 1989).
Species Status: Considered a single species -- ambitiosus -- until Gross et al. (1989) recognized three additional siblings based on songs, electrophoretic analysis, and at least partially on morphological differences. Specimens collected by Fulton (listed by Brimley, 1938), were identified as ambitiosus, but could be either the species now recognized as ambitiosus or hubbelli, which can only be distinguished by song. Both have been documented in South Carolina and seem equally likely to be the one collected by Fulton; the other two species have only been recorded in Florida or extreme southern Georgia. Although Fulton (1931) describes the song of ambitiosus, his account was based on individuals he heard in Florida and he lacked the equipment required to make an accurate measurement of pulse rate, which is needed to distinguish ambitiosus from hubbelli.
Identification
Field Guide Descriptions: Online Photographs: SINA, BugGuide, Google ImagesTechnical Description, Adults/Nymphs: Hebard (1913); Gross et al. (1989)                                                                                  
Comments: A small, reddish-brown ground cricket. Members of this genus are distinguished by their facial markings: the face is shining black, with a narrow pale stripe between the eyes (Hebard, 1913). The vertex is also shining black but the occiput is reddish brown, similar to the color of the pronotum. In ambitiosus and hubbelli, the tegmina of the males have a pale margin that includes the tips of the wings. (Hebard, 1913; Gross et al., 1989). Hebard noted that the hind femur has a conspicuous stripe on the outer side, but Gross et al. found that character in all of the species except arenicola.
Total Length [body plus wings; excludes ovipositor]: 5.9-8 mm, males; 6-8.2 mm, females (Hebard, 1913; possibly refers to a mixture of species)
Structural Features: Hindwings are absent (Gross, et al., 1989)
Singing Behavior: Songs consist of a series of short trills (chirps) given at regular intervals. The length of trills measured for ambitiosus in Florida is about 0.5-0.7 sec, but is greater than 1 second in populations in South Carolina (Gross et al., 1989). Pauses between trills are about the same length as the trills themselves. Each trill is composed of a series of nearly vertical pulses, which gives the song a somewhat buzzy quality. In ambitiosus, the pulse rate is about 44-54 pulses per second at 77 F (= 25 C) (Gross et al., 1989). The dominant frequency at that temperature is around 6.7 (SINA). As noted by Fulton (1931) and evident in spectrograms at the Macaulay Library, each trill increases in amplitude from start to finish.
Recording playback at normal speed.

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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: Most of the species in this genus are associated with dry, open, oak woodlands growing on sandhills. At least some populations of ambitiosus in South Carolina, occur in river bottomlands or stands of mesic hardwoods (Gross et al., 1989).
Diet: Probably omnivorous
Observation Methods: Males sing primarily during the day and are most easily detected by their songs
Abundance/Frequency:
Adult Phenology: Records for ambitiosus from South Carolina are all from the summer and fall (Gross, et al., 1989)
Status in North Carolina
Natural Heritage Program Status: [W3]
Natural Heritage Program Ranks: [GNR] S1S3
State Protection: Has no legal protection, although permits are required to collect it on state parks and other public lands
Comments: Members of this genus have been rarely collected even in South Carolina and the only records we have from North Carolina are the ones collected by Fulton in the 1930s. Although more needs to be learned about the species we have, their distribution and abundance, and their habitat associations, Gross et al. (1989) found that populations appeared to be highly isolated from one another, as demonstrated by large differences in their electrophoretic allozymes and other characters. In habitat species, such as these species seem to be, the lack of dispersal often means that they are highly vulnerable to the effects of habitat fragmentation. There is at least the possibility, therefore, that this species (or group of species) could be of significant conservation concern in North Carolina.

Image Gallery for Pictonemobius ambitiosus complex

Recorded by: Steve Hall and Bo Sullivan
Scotland Co.
Comment: 45 pulses/sec; ~80 F; old field adjoining pine-scrub oak sandhills