Pteronemobius Jacobson, 1904

Hegg, Danilo, 2024, Small crickets of New Zealand (Orthoptera: Grylloidea: Trigonidiidae and Mogoplistidae), with the description of two new genera and species, European Journal of Taxonomy 955 (1), pp. 1-87 : 45-46

Genus Pteronemobius Jacobson, 1904

Pteronemobius Jacobson in Jacobson & Bianchi, 1904: 450.

Pteronemobius – Otte & Alexander 1983: 164–167, figs 124–125, table 10. — Rentz & Su 2019: 335– 336, table 9.

Type species

Pteronemobius heydenii tartarus (Saussure, 1874) by designation.

Etymology

From the Ancient Greek πτερόν (‘pterón’), ‘wing’. Pteronemobius means ‘winged Nemobius ’. In contrast to the wingless genus Nemobius Serville, 1838 , Pteronemobius often have hindwings and are able to fly. Pteronemobius is male gender. Ground crickets in this genus are often referred to as ‘common pygmy crickets’ in English.

Diagnosis

Highly variable in size, from small to relatively large ground crickets, with a body length between 4 mm and 9 mm depending on species; coloration variegated light to dark brown. Forewings fully developed in both sexes and exceeding the combined length of head and pronotum. Twenty-five to forty percent of females have short forewings ( Fig. 28B, F ); 20% to 25% have long forewings ( Fig. 28C, E ). Hindwings are present in up to 40% of individuals in both sexes ( Fig. 28C, F ). Stridulatory apparatus complete. Tympana present on posterior side of Tibia I. Tibia III with three or four outer and four inner subapical spurs in both sexes, alternate. The fourth inner subapical spur in males is small, glandular ( Figs 23C , 25C ). Length of Tibia III outer ventral apical spur approx. 80% that of ventral inner apical spur. Length of Tarsomere III-1 outer apical spur approx. 50% to 60% that of inner apical spur.

Measurements

See Table 6 . No sexual dimorphism in body length.

For a detailed description of this genus in the Australian region, see Otte & Alexander (1983: 164–167); Rentz & Su (2019: 335–336).

Habitat and ecology

Primarily nocturnal singers, may start singing in the late afternoon or evening on overcast days. Most commonly found next to water, or in saturated meadows.

Distribution

In New Zealand, primarily in North Island, but range expanding; Pteronemobius truncatus was first recorded in the northern South Island in March 2023 (iNaturalist 152116367). Not a New Zealand native genus; both species are recent introductions from Australia. Also found on Nortfolk Island; possibly in New Caledonia.

Remarks

The genus Pteronemobius currently includes 104 species spread across all continents except for Antarctica ( Cigliano et al. 2023). The type species is Pteronemobius heydenii tartarus (Saussure, 1874) , from the regions surrounding the Caspian Sea. Chopard (1951) moved the Australian species Nemobius truncatus Saussure, 1877 to Pteronemobius based on the presence of a glandular subapical spur (tsai4) on the inner edge of Tibia III in males. Vickery (1973) defined the tribe Pteronemobiini based on the same character and noted that “many species which still remain in Pteronemobius (sensu Chopard) should be studied”, and that “ Pteronemobius (sensu Chopard) is a heterogeneous assemblage, according to current morphological and cytological information”. Nonetheless, Otte & Alexander (1983) and Rentz & Su (2019) kept the Australian species in Pteronemobius ; the former in fact added several species to the genus. Desutter-Grandcolas (2016) designated the new genus Caledonina from New Caledonia, which also has a glandular subapical spur on Tibia III in males, but placed it in the tribe Nemobiini based on molecular data, noting that her data “validate the occurrence of species with a tibial gland in males within the Nemobiini , a character used up to now to separate Pteronemobiini ”. Indeed, the male genitalia of Caledonina chopardi Desutter-Grandcolas, 2016 strongly resemble those of the Australian species Pteronemobius regulus ( Saussure, 1877) (compare Desutter-Grandcolas 2016: fig. 9f–h with Otte & Alexander 1983: fig. 130j). Based on this information, I believe the two species included here in Pteronemobius may not belong to this genus at all and could even be placed in the wrong tribe. It is, however, outside of the scope of this work to resolve the wider systematics of Nemobiinae from the Australian region. The brief diagnosis for Pteronemobius given here is based on Rentz & Su (2019), is valid for species of Pteronemobius in the Australian region, and may not apply to Pteronemobius s. str.

Figures

Fig. 28. Live Pteronemobius Jacobson, 1904. A–C. Pteronemobius truncatus (Saussure, 1877). A. Adult ♂, Kohuroanaki Loop Track, Te Paki, Northland. B. Adult ♀ with short forewings. Awakino, Waikato. C. Fully winged adult ♀. Leitchs Clearing, Herangi Range. D–F. Pteronemobius cf. arima Otte & Alexander, 1983. D. Adult ♂, Auckland. E. Fully winged adult ♀. Kerikeri, Northland. F. Adult ♀ with short forewings. Kerikeri, Northland. Note: all specimens are posed on unnatural backgrounds in captivity.

Fig. 23. Pteronemobius truncatus (Saussure, 1877). A–B. Lateral and frontal view of head, adult ♀. Herangi Range (MPN OR0219). C. Glandular sub-apical spur (tsai4) on dorsal inner edge of tibia III in adult ♂. Cambridge, Waikato (MPN OR0214). D. Left hindwing in female, dorsal view. Cambridge, Waikato (MPN OR0346). E. Egg. Coromandel (MPN OR0397). F–G. Apex of ovipositor. Herangi Range (MPN OR0219). F. Dorsal view. G. Lateral view. H. Ovipositor, lateral view. Cambridge, Waikato (MPN OR0204). Scale bars = 500 μm.

Fig. 25. Pteronemobius cf.arima Otte &Alexander, 1983. A–B. Lateral and frontal view of head, adult♀. A. Spirits Bay, Northland (MPN OR0248). B. Kerikeri, Northland (MPN OR0223). C. Glandular subapical spur (tsai4) on dorsal inner edge of tibia III in adult ♂. Kerikeri (MPN OR0234). D. Egg. Maitai Bay, Northland (MPN OR0366). E–F. Apex of ovipositor. Spirits Bay (MPN OR0248). E. Dorsal view. F. Lateral view. G. Ovipositor, lateral view. Kerikeri (MPN OR0225). Scale bars = 500 μm.