Crickets of the genus Gryllus in the United States (Orthoptera: Gryllidae: Gryllinae) Author Weissman, David B. Author Gray, David A. text Zootaxa 2019 2019-12-05 4705 1 1 277 journal article 24722 10.11646/zootaxa.4705.1.1 3e84f284-4d30-4c6e-a801-f9822d49edfc 1175-5326 3563677 F534C43A-AB09-4CB3-9B08-FD5BDFD90298 Gryllus rubens Scudder Southeastern Field Cricket Figs 71–82 , 85 , 86 , 90 , Table 1 1902 Gryllus rubens Scudder. Psyche 9: p. 295. Holotype female, Auburn, Alabama . Type in ANSP, photos ( Fig. 74 ) courtesy of J.D. Weintraub, ANSP. Plotting Scudder’s female holotype measurements of pronotal width of 6 mm and ovipositor length of 16 mm ( Scudder 1902 ) falls within G. rubens measurement cluster ( Fig. 75 ). 1957 Acheta rubens (Scudder) . Alexander, 1957 . p. 586. 1964 Gryllus rubens Scudder. Randell 1964 . Distribution. One ( Fig. 71, R13-220 ) of only two trilling US Gryllus found between 99° longitude (central Texas ) and the Atlantic coast. See Walker (2019) and Gray (2011) for additional eastern localities. Recognition characters and song. Medium sized, short or long hind winged crickets with an average PR of ~55 at 25°. Distinguished from morphologically similar and trilling, sometimes sympatric, G. texensis in that the latter has an average PR of ~80 at 25° ( Figs 71 , 84 ), more teeth in the file ( Figs 78 , 79 ), a shorter ovipositor ( Gray et al . 2001 ), and frequently, but not always, shorter bursts of pulses. Pulse rate at a given temperature faster, but with greater separation from G. texensis , in the late summer/fall generation than in the spring generation ( Walker 1998 ). Along coastal Texas , in 2013, we found no overlap in dominant frequency, in many males, which was <5000 Hz in G. rubens but>5000 HZ in G. texensis . Yet around Tulsa , Oklahoma (S13-68), there is overlap and we wonder if this might reflect hybridization, environmental effects during development, or both. Additionally, Blankers (pers. comm.) stated that dominant frequency values that he used in Blankers et al. (2015) had a range of 4.18–5.88 KHz in G. rubens and 4.66–5.56 KHz in G. texensis . Unfortunately, these measured males were all from laboratory generations with unknown effects on the song. Derivation of name. “rubens” apparently for the general reddish and rufo-testaceous markings on Scudder’s unique, long tegmina female specimen. Geographic range. ( Fig. 76 .) Most of our collection localities are near the western and northwestern boundaries of G. rubens’ distribution. See Gray (2011) and Walker (2019) for more complete eastern US distribution maps. Our most western locality is Bastrop State Park (S91-23), Texas , where G. rubens occurred with G. texensis . There we collected one male G. rubens (R91-39) with a PR of 53 at 25°C and with 100 file teeth and three G. texensis (R91-5, 6, 7) with PRs from 80–100 at 25°C and with 110–121 file teeth. We could not distinguish these two songs in the field. FIGURE 71. Five second waveforms of calling songs of (A) G. rubens , (B) G. texensis , and (C) G. regularis . (A) G. rubens : (R13-220) Tulsa , OK (S13-68), at 25°C; (B) G. texensis : (R13-224) Rio Hondo, TX (S13-44), at 26°C; (C) G. regularis (R99- 211) Sinaloa, MX (S99-86), at 25.5°C. FIGURE 72. One second spectrograms of (A) G. rubens , (B) G. texensis , and (C) G. regularis , same males as in Fig. 71. FIGURE 73. ITS2 gene tree. G. rubens samples: Orlando, FL (F122); Lake City & Ocala, FL (Genbank SRA, Berdan et al . 2016 ); G. regularis samples: S07-2 (G1101); S07-41 (G1085); S15-67 (G3154); S15-102 (G3280); G. texensis samples: S15-43 (G3048); S16-12 (G3382, G3403, G3404, G3421); Uvalde, TX (d102); Bastrop, TX (d1042). FIGURE 74. Holotype female G. rubens , with labels. Habitat. Lawns, pastures, and grassy roadsides. Life cycle and seasonal occurrence. No egg diapause. Two generations/year even at the northern extremes of its range ( Capinera et al . 2004 ). Adult peak abundances in spring and fall, representing the separate generations. Continuous generations in Florida ( Vélez & Brockmann 2006 ). Can be locally common. FIGURE 75. Regression of pronotum width vs. ovipositor length in the only two trilling eastern US taxa shows that holotype most consistent with G. rubens . Variation. Hind wing length: Populations variable for short and long hind winged individuals of both sexes ( Veazey et al . 1976 , Walker 1987 ). Color: Within a population (e.g. S02-58, Missouri ), individuals ( Fig. 80 ) may have black hind femurs and tegmina compared to more typical brown/reddish ones. Pronotum: Usually very shiny in males, possibly less so in females. Song: Usually an evenly spaced trill but one male from Missouri , with 95 file teeth, ( Fig. 81 , R02-74, S02-58) with variable grouping of pulses. Specimens examined. (Total: 54♂ 27♀ ). Arkansas: Garland Co., Jessieville, 19-vi-1993 , 750’ (S93-46) 1♂ . Yell Co. , Dardonelle , 19-vi-1993 , 400’ (S93-48) 2♂ . Florida : Alachua Co., Gainesville , 2-x-1986 (S86-128), TJ Walker , 20♂ 7♀ . Indiana : Warrick Co. , 4 m S Dale 4-vi-2003 , 650’, 38° 7.228’ -87° 1.591’ (S03-61) 1♂ . Maryland : Prince George Co. , College Park , 30-v-2004 , 500’ (S04-35) 2♂ . Missouri : Cape Girardeau Co. , Millersville , 9-viii-2002 , 320’ (S02-58) 6♂ 9♀ ; Iron Co., Pilot Knob , 9-viii-2002 , 840’ (S02-57) 2♂ 1♀ . Oklahoma : Texas Co. , Guymon , 1-vii-2009 , 3380’ (S09-77) 1♂ . Tulsa Co., Lake Keystone Dam area, 22-v-2001 , 650’, 36° 9.092’ -96° 15.043’ (S01-47) 1♂ ; Tulsa , 15-vii-2013 , 775’ (S13-67, 68) 9♂ . Texas : Bastrop Co. , Bastrop State Park , 31-v-1991 , 700’ (S91-23) 1♂ . Galveston Co. , High Island , 10-vi-2011 , 5’ (S11-28) 4♀ . Harris Co. , Cypress , 148’, 13-vii-2013 (S13-64) 3♂ . Jefferson Co. , Sabine Pass , 10-vi-2011 , 20’ (S11-31) 3♂ 5♀ ; Sea Rim State Park , 10-vi-2011 , 5’ (S11- 29) 1♀ ; Marion Co. , Caddo Lake State Park , 18-vi-1993 , 300’ (S93-42) 1♂ . Orange Co. , Beaumont , 1-vi-1991 , 50’ (S91-32) 1♂ . DNA. Multilocus d437 from Florida , Jackson Co., Marianna, 28-ix-1999 , 117’, 30.774°, -85.227°, pulse rate in this male 53 at 25°C. Closest relatives (Gray et al. 2019): G. texensis (see Gray 2006; Gray et al. 2006 ) and G. regularis . See also Blankers et al. (2018) , which compared transcriptomic genetic variation in G. rubens and G. texensis . In that study, several loci were fixed for genetic differences between G. rubens and G. texensis , so in principle there are diagnostic genetic differences between these taxa, but they are not applicable in any practical sense. Discussion. When standing near simultaneously trilling males of G. rubens and G. texensis , one can sometimes hear subtle differences between the two songs, probably reflective of the different pulse rates and dominant frequencies. Currently, there is no single, definitive morphological character that separates male G. rubens from male G. texensis ( Walker 1998 , Gray et al . 2006 ), although we do present new data ( Fig. 79 ) showing promise when comparing number of file teeth vs. teeth/mm. In the past, positive male identification has been exclusively linked to differences in song PR . Unfortunately, the ability of this one song parameter to separate the two species gets murky in some populations. Gray & Cade (2000a) demonstrated an increase in PR in G. rubens of ~3 for each 1°C rise in temperature and an increase in PR in G. texensis of ~5 for each 1°C rise. Martin et al . (2000) demonstrated an increase in PR of 3.5 for every 1°C increase in recording temperature in G. texensis (called “ G. integer ” by Martin et al. 2000 ). We applied a modification of this temperature correction (+4 pulses for each 1°C difference from 25°C because we did not want to prejudge which species that we decided that we were recording) to 16 males from Tulsa , OK (S13-68) recorded in the laboratory between 22–28°C and whose PR we normalized to 25°C: we find no unambiguous separation at this locality and get only a modestly bimodal PR ( Fig. 82 ). FIGURE 76. Populations of G. rubens that we studied. While we did not find this ambiguity, in pulse rate, to be geographically widespread, it is also not unique: For instance, Walker (1998 , p. 175) notes: “…songs I attributed to G. rubens had a slightly higher average pulse rate in the zone of overlap [with G. texensis between western Florida and eastern Texas ] than farther east and both species varied more in pulse rate between individuals from the same site and for the same individual from time to time than in the many other cricket species I had studied. G. rubens and texensis [called ‘ G. integer ’ by Walker in 1998] were not as clearly separated by their songs as other sympatric pairs of sibling species of crickets.” FIGURE 77. One second waveform, pulse rate of 56, of calling song of G. rubens : (R13-220) Tulsa , OK (S13-68), at 25°C. FIGURE 78. Regression of number file teeth vs. hind femur length showing separation of sympatric G. rubens from G. texensis . Instead of finding character displacement where they overlap, Walker (1998) found the opposite and concluded that the two species may hybridize in areas of overlap in western Florida . Such hybridization is achievable in the laboratory ( Smith & Cade 1987 ), but, based on song phenotype, appears to be rare in sympatry ( Izzo & Gray 2004 ). Nonetheless, we wonder if they may be hybridizing at our Tulsa , OK, site (S13-68), as discussed above. Using transcriptomic data, Blankers et al. (2018) found no evidence of interspecific gene flow more recently than ca. ~18K years, but, it must be noted, the source populations for that study were from allopatry. Additionally, Walker (1998) documented that different generations have different pulse rates, now further investigated by Beckers et al. (2019) , so variable environmental effects are certainly possible. G. rubens has been used in hybridization studies ( Smith & Cade 1987 ; Cade & Tyshenko 1990 ), tachinid fly parasitism ( Vélez & Brockmann 2006 ), effect of temperature on pulse rates ( Doherty & Callos 1991 ; Walker 2000 ), female phonotaxis ( Doherty & Callos 1991 ), song character displacement ( Walker 1998 ; Izzo & Gray 2004 ), courtship song divergence ( Fitzpatrick & Gray 2001 ) and impact on potential for hybridization ( Gray 2004 ), peripatric speciation ( Gray et al . 2008 , Blankers et al. 2018 ), genetics of speciation ( Blankers et al. 2019 ), aggressiveness related to habitat ( Jang et al. 2008 ), and male response to conspecific song ( Jang 2011 ). Past research is summarized in Gray (2011) .