Gryllus lineaticeps Stål

Weissman, David B. & Gray, David A., 2019, Crickets of the genus Gryllus in the United States (Orthoptera: Gryllidae: Gryllinae), Zootaxa 4705 (1), pp. 1-277 : 168-175

Gryllus lineaticeps Stål

Variable Field Cricket

Figs 170–178 , Table 1

1860 Gryllus lineaticeps Stål, 1861 [1860]. Kongliga Svenska fregatten Eugenies Resa omkring jorden under befäl af C.A. Virgin åren 1851–1853. Zoologi 1. p. 314. Type locality: California, San Francisco. Type female lost according to Alexander (1957). Neotype male ( Fig. 175 ) designated by Weissman et al. (1980): “ California, Santa Clara Co., Palo Alto, Stanford University campus, Lake Lagunita, 4-vii-1979. David B. Weissman,” CAS Entomology type #13221. Body length 23.7 mm; right tegmen removed, file with 136 teeth, 3.9 mm long.

1977 ‘ Gryllus III’. Weissman & Rentz (1977a).

1980 Gryllus lineaticeps Weissman et a l. (1980).

1981 ‘ Gryllus III’. Rentz & Weissman (1981).

‘ Gryllus #3’ of DBW notebooks.

Distribution. Restricted to southwestern Oregon, California (including all of the 8 California Channel Islands except San Miguel), and most of Baja California, Mexico.

Recognition characters and song. Medium to very large crickets (see Table 1 , p. 18), widespread and ecologically diverse but prefer grassland habitats. Song ( Fig. 176 ) loud, unique within its range: fast chirper, at 25°C, typically with 6 to 9 (range 5-11) pulses, frequently 150 to 250 chirps/min, pulse rate usually between 40-65 (range 32 to 83), dominant frequency 5 kHz. Two generations/year. Color variable, from red ( Fig. 177 ) to black, within a population and between generations: first generation winter and spring adults usually darker (many black) than summer adults (many tan to reddish brown). Among western US taxa with a similar song, differs from sometimes sympatric G. multipulsator which has more pulses/chirp, slower chirp rate, dull (hirsute) pronotum and different microhabitat. Differs from allopatric sister species G. personatus which has a pale area around eye, longer ovipositor, slower chirp rate and essentially complete separation in dominant frequency ( Fig. 173 and Gray et al. 2016b). Differs from allopatric sister species G. staccato which has variable pulses/chirp and faster pulse rate ( Fig. 173 and Gray et al. 2016b).

Derivation of name. “line” = line; “ceps” = head or “lines on the head,” indicating that perhaps the lost holotype appeared as such. Second generation specimens (including the neotype, which is from Palo Alto, CA, or some 50 km south of the type locality), especially those light-colored individuals from hot, dry locales, frequently have dark, linear stripes on the head. This condition is also commonly found in the sister taxa G. personatus and G. staccato but is not restricted to these Gryllus species, or even to the genus Gryllus in the Gryllidae .

Geographic range. See Fig. 178 . Generally west of the Sierra Nevada but individuals east of the Sierra Nevada collected at Mono Lake (S78-125), Lone Pine (S78-117) and in the Mohave Desert at Barstow (S98-58 & S98-77) and the town of Mohave (S05-117). Collected on all of the 8 California Channel Islands except for San Miguel.

Habitat. Easily the most common and loudest, low elevation, California summer grassland field cricket west of the Sierra Nevada. In winter and spring, late instars and newly molted adults of the first generation found under rocks and boards. In summer, males of the second generation sing from substrate cracks in grasslands, chaparral, coastal sage, oak-woodlands and around human habitation. Usually found below 1000 m elevation, but found over 2400 m in Mexico (Weissman et al. 1980).

Life cycle and seasonal occurrence. No egg diapause (checked from Santa Clara Co., CA, S92-44) in either generation. Two generations/year (as least as far north as Santa Clara Co.). Overwinters as late instars with first adults in warmer parts of southern California singing during daytime as early as December. On 17-xii-1996, a few newly molted adult males and females, plus hundreds of late instars, found at California, Monterey Co., Hwy 198 at mile post 15.0 (S96-111), 411-457 m elevation. Second generation numbers larger with adult males heard starting in early summer. Unknown if a second generation occurs in northern California and southwestern Oregon localities.

Variation. Color (see Fig. 177 ): body, pronotum, head, wings, and hind femur usually variable between black to red within individuals at one locality. First generation individuals usually dark. Second generation, especially from dry, hot areas like the Central Valley, usually more reddish. Beach specimens generally light colored all over. Pulses/chirp. One male (San Clemente Island, R18-16, S18-24) with 11 pulses/chirp, more than seen elsewhere for this taxon. Wing length: Variable. Of 80 males, 16 had long hind wings. Of 60 females, 18 had long hind wings including all 10 females collected from California, Fresno Co., Coalinga (S98-86), 29-vii-1986.

Specimens of note (mostly from edges of distribution). Complete locality list not given because G. lineaticeps is common and widely distributed wherever it occurs.— CALIFORNIA: El Dorado Co., Finnon Reservoir, 29-iii- 2005, 2340’ (S05-39). Fresno Co., Coalinga, 29-viii-1998 (S98-86); Jacalitos Canyon, 29-viii-1998 (S98-82 & 98- 83). Inyo Co., Lone Pine , 5-viii-1978 (S78-117). Kern Co., Mohave, 1-ix-2005 (S05-117); Tehachapi, 28-v-2009, 3320’ (S09-28). Mendocino Co., 4 m E Longvale, 2-viii-1980, 1000’ (S80-59). Mono Co., Mono Lake, 7-viii-1978 (S78-125). San Bernardino Co., Barstow, 16-viii-1998, 2420’ (S98-58) & 21-viii-1998 (S98-77). San Joaquin Co., Tracy, 52’, 10-ix-2016, RE Espinoza. San Mateo Co., Stanford University’s Jasper Ridge Biological Preserve, 2-v- 1992 (S92-44). Shasta Co., Shasta Dam, 4-viii-1980 (S80-66). Yolo Co., I5 near intersection Hwy 505, 19-viii-2006, 130’ (S06-77). OREGON: Jackson Co., Emigrant Lake Recreational Area, 27-vii-1992, 1800’ (S92-82). Hwy 66 ~ 12 m E I5, 2900 ’, 27-vii-1992. Josephine Co., Hugo, 25-vi-1978, D.C. Lightfoot.

DNA. Multilocus 2016-033 (Tracy, CA). Two sister species (Gray et al. 2019) are G. personatus (multilocus G1357 from Otero Co., Colorado) and G. staccato (multilocus 2016-034 from Yavapai Co., AZ). 16S and ITS2 ( Fig. 174 ) gene trees yields nice separation from sister species G. personatus and G. staccato . In our early work, CO1 gave less clear separation between species, but also showed highly suspect signs of pseudogene amplification.

Discussion. An ecologically diverse and morphologically variable species, although song, file characters and DNA consistent for one species. Responsible for periodic outbreaks in California’s Central Valley with documented episodes in Coalinga as follows: 1967, R.E. Love, pers. comm.; Lindgren (1978); Caruba (1980), and DBW (un- publ.) on 28-vii-1998; where millions of macropterous, flying individuals can become a summer nuisance. This is probably the species responsible for the outbreak in Knightsen, Contra Costa Co., CA, in 2001 (https://www.sfgate. com/bayarea/article/Knightsen-crawling-with-crickets-Vacuums-2872987.php).

Those summer males singing from grassland cracks are usually impossible to flush with water given the extensive nature of the cracks. Oatmeal trails there will usually attract females and occasionally males.

Not all Gryllus species with long hind wings are good flyers. G. lineaticeps seems to be a very capable flyer as evidenced by its presence on seven of eight California Channel Islands (Weissman et al. 1980), and Cedros and Guadalupe Island, Mexico, the latter some 240 km west of the Pacific coast of Baja California (DBW, unpubl.), although other means of colonization are possible.

This species has been the subject of a series of studies of sexual communication, e.g. Hoback & Wagner (1997), Wagner & Harper (2003), Wagner & Basolo (2007a), and Tolle & Wagner (2011) as well as studies of tachinid fly parasitism, e.g. Gray et al. (2007), Wagner & Basolo (2007b), Martin & Wagner (2010), Paur & Gray (2011a), and Beckers & Wagner (2012, 2018), and female reproductive benefits ( Wagner 2005).

Figures

FIGURE 170. Five second waveforms of typical calling songs of (A) G. lineaticeps, (B) G. personatus, and (C) G. staccato. (A) G. lineaticeps: (R11-15) Mendocino Co., CA (S11-22), recorded at 24°C; (B) G. personatus: (R07-74) from Alpine, TX (S07-41), recorded at 25°C; (C) G. staccato (R15-291) from Gila Bend, AZ (S15-111), recorded at 25.1°C.

FIGURE 171. One second spectrograms of typical calling songs of (A) G. lineaticeps, (B) G. personatus, and (C) G. staccato, same males as in Fig. 170.

FIGURE 172. Known distribution (from Gray et al. 2016b) showing, basically, allopatric localities of the three Lineaticeps Group taxa.

FIGURE 173. Separation of species within the Lineaticeps Group by song (from Gray et al. 2016b). Most points represent lab-reared individuals; therefore, it is possible that field-caught individuals (see Table 1, p. 18) would show somewhat less clear separation given known effects of developmental temperature on song in field crickets (Walker 2000).

FIGURE 174. ITS2 gene tree. Collection stop numbers for G. lineaticeps samples: S00-15, Guadalupe Island, Mexico (G273); S04-64 (G352); S05-39 (G463); S09-28 (G1303); S09-37 (G1315). Collection stop numbers for G. personatus samples: S99- 84, Durango, Mexico (G393); S03-127, from Coahuila, Mexico (G75, G76); S07-41 (G1014); S09-58 (G1372); S09-151, from near Janos, Mexico (G1462, G1463); S16-6 (G3371). Collection stop numbers for G. staccato samples: S04-121 (G376); S09- 54 (G1397); S09-103 (G1407); S11-102 (G2186). See also Gray et al. (2016b).

FIGURE 175. Neotype male of G. lineaticeps, with labels.

FIGURE 176. Calling song (R11-15) of G. lineaticeps from Mendocino Co., CA (S11-22), recorded at 25°C; lower panel shows structure of a single chirp.

FIGURE 177. Color variation in G. lineaticeps: Reddish male (A) and female (C) from Madera Co., CA (S15-91); black male (B) from Tuolumne Co., CA (S10-13).

FIGURE 178. Known US distribution of G. lineaticeps.