Gryllus thinos Weissman & Gray, 2019

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 : 42-46

Gryllus thinos Weissman & Gray , n. sp.

Texas Beach Field Cricket

Figs 24–27 , Table 1

‘ Gryllus #21’ and ‘near #21’ of DBW notebooks.

Distribution. Texas—restricted to Texas Gulf coast and up to 8 km inland.

Recognition characters and song. Small to medium sized ( Fig. 24 ), always short hind wings, medium length cerci, almost always in sandy habitats, males frequently sing from up in vegetation. Song ( Fig. 25 ; R07-125) a slow chirp, CR usually <90, 4–7 p/c, PR 20–35. Can be distinguished from only other Texas Gulf coast, sandy-environment field cricket, G. firmus (Texas) , by DNA, non-overlapping file teeth, teeth/mm and a generally lower PR ( Table 1 , p. 18). Singing males of G. thinos also easier to approach than singing, microsympatric G. firmus . Females of the two taxa can be difficult to separate although G. firmus ovipositor length is generally longer in that larger species (see Table 1 ).

Holotype. Male ( Fig. 24 ). USA, Texas, Kleberg Co., Padre Island National Seashore around Malaquite Visitor Center , 11-vi-2011, 15’. 27° 25’ 23.2” -97° 18’ 07.7”. D.B. Weissman. S11-35, R11-8, DNA sample G2018. 16 S GenBank accession # MK 446632 . BL 17.28, HF11.53, LC 10.76. Right tegmen removed: 119 teeth, file length 3.1, TL 10.0, TW 4.6. Type deposited in CAS, Entomology Type #19274.

Paratypes. ( Total : 67♂ 14♀) Texas. Aransas Co., Business 35 near Rockport, 10’, 12-vii-2013, 27° 57’ 32.7” -97° 06’ 14.4” (S13-55) 1♂ . Texas 188 0.2 m SE Hwy 35, 19’, 12-vii-2013, 27° 57’ 56.1 -97° 07’ 13.7” (S13-54) 2♂. Cameron Co., Boca Chica State Park, 10’, 25° 59.827” -97° 09.146” 3-vi-1991 (S91-36) 5♂ 1♀ ; 10-vi-2007 (S07-25) 6♂ 4♀ . South Padre Island , Isla Blanca Park, 5’, 10-vii-2013, 26° 04” 09.3’ -97° 09” 41.7 (S13-41) 3♂ . Kleberg Co., Padre Island National Seashore , near Park entrance, 11-vi-2011, 27° 28” 39.9’ -97° 16” 28.7’ (S11-34) 1♂ . Malaquite Visitor Center , 11-vi-2011 (S11-35) 2♂ 3♀ ; 3 m N Malaquite Visitor Center , 2-vi-1991 (S91-33) 11♂ 5♀ ; South Beach , 2-vi-1991 (S91-34) 2♂ . Matagorda Co., Hog Island , 21’, 13-vii-2013, 28° 36’ 17.4” -95° 57’ 34.8” (S13-60) 4♂. Nueces Co., Corpus Christi near 10421 S. Padre Island Dr., 27° 40’ 02.5” -97° 16’ 54.4”, 29-vi-1986 (S86-57) 20♂ 1♀ ; 12-vii-2013 (S13-53) 1♂ . Mustang Island State Park , 5’, 12-vii-2013, 27° 40’ 25.9” -97° 10’ 30.1” (S13-51) 7♂ . Hwy 361 2 m S Port Aransas, 12-vii-2013, 15’ (S13-52) 2♂ .

Derivation of name. “thinos” is Greek for beach, shore, or strand in recognition of where this cricket occurs.

Geographical range. Fig. 26 . Known only from coastal and barrier island areas of Texas and inland for no more than 8 km. May get into adjacent coastal Mexico but areas not checked due to limited access. We did find suitable sandy areas just south of Tampico, Mexico, and around Galveston, Texas, but no G. thinos at either site.

Habitat. Almost always on sandy substrate in open, low rolling coastal dunes. In Corpus Christi (S86-57 and S13-53), somewhat sandy-substrate vacant field with grasses, forbs, and small shrubs (all three vegetation types from 10 to 40 cm tall), males almost always singing from vegetation (but never at top of plants) and initially visible on triangulating but quickly climbed (not jumped) down. Also heard throughout town of Corpus Christi in 1986 in road median areas, mowed lawns, etc. At Padre Island National Seashore (S91-33), common, with some in plants, but many just along mowed edges of road in vegetation 5 cm tall and singing with females also walking around. At Padre Island National Seashore (S11-34), nymphs and one adult male collected under boards just above high tide line. At Mustang Island State Park (S13-51), several reddish/pale mid instar nymphs under boards on low rolling dunes during daytime. At night at Mustang Island, all 7 singing males 15 to 46 cm up in grass, dead twigs, and Yucca spp. Two of those males quickly climbed down and retreated into nearby holes in the sand and were easily flushed with water.

Life cycle and seasonal occurrence. No egg diapause: Corpus Christi (S86-57). Probably one generation/year but many late spring and early summer mid-instar nymphs, at Padre Island National Seashore (S91-33) and Mustang Island State Park (S13-51), either represent a second generation or, more likely, show that maturation occurs over several months. Mid instar nymphs from those two localities molted to adults in August.

Variation. Color: tegmina almost equally divided between brown and black. Rear leg femur and tibia usually tan/orange but also black. Head: 13 adult males (out of 67) and 3 adult females (out of 14) with defined linear head stripes ( Fig. 24 ), a character also seen in some late instars.

DNA. Multilocus G1209 (Boca Chica State Park, TX, S07-25) maps (Gray et al. 2019) with 2 males from Cor- pus Christi, TX (G2018, G2022 from S11-35). Surprisingly, the single, fall generation, egg diapausing G. ovisopis appears to be the sister species.

Much DNA variation between habitats although no morphologically corresponding characters. When South Padre Island specimens (S11-35) were genetically compared with those from Boca Chica (S07-25), less than 200 km south and in a similar habitat, we found, for CO1, 17 fixed nucleotide differences in 700+ base pairs; and for 16S, 6 fixed nucleotide differences in 500+ base pairs. We are concerned, however, that the COI variation might be an artifact of pseudogenes (see general DNA discussion, pages 16 & 17). ITS2 also shows very slight separation within G. thinos from these localities ( Fig. 27 ). Further analysis might support species status for these genetically very different populations but in a comparison of their morphological characters (see Table 1 , p. 18), nothing stands out. Plus, all 3 individuals are each other’s nearest neighbor in multilocus tree. The Boca Chica habitat, while appearing very similar to Padre Island, is somehow ecologically different in that the former locality is also inhabited by microsympatric G. firmus , while no other Gryllus species occurs on Padre Island.

The Texas beach inhabiting crickets, G. thinos and G. firmus (Texas) , are clearly genetically distinct: Tamura- Nei genetic distance within G. thinos ITS2 samples is low (N = 6, mean ± SD, 0.0044 ± 0.0037), similar to variation within G. firmus (Texas) samples (N = 12, mean ± SD, 0.0034 ± 0.0040), but an order of magnitude greater between G. thinos and G. firmus (Texas) (0.0240 ± 0.0027 mean ± SD).

Discussion. Singing males easy to approach. On 10-vi-2007, males not singing well until 21:45, considerably after sunset, and without a significant moon. Oatmeal trails in dunes helped to attract wandering individuals.

Besides finding G. thinos microsympatric with G. firmus at Boca Chica, we also found them together near Port Aransas (S13-52), and Mustang Island State Park (S13-51). Singing males of the two species are easily separated in the field by the slower pulse rate in G. firmus .

Figures

FIGURE 24. Holotype male (left), G. thinos. Female (right) from type locality showing typical, linear head stripes.

FIGURE 25. Calling song of G. thinos (R07-125) Cameron Co., TX (S07-25), at 25°C: (A) five second waveform, (B) one second spectrogram.

FIGURE 26. Known distribution of G. thinos.

FIGURE 27. ITS2 gene tree showing some separation between Padre Island and Boca Chica samples of G. thinos.