Pteronemobius truncatus ( Saussure, 1877 )

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 : 48-51

Pteronemobius truncatus ( Saussure, 1877)

Figs 5–7 , 8A–B , 23–24 , 27A–F , 28A–C , 38E

Nemobius truncatus Saussure, 1877: 259 .

Nemobius laparinthae Tepper, 1896: 378 .

Pteronemobius mjobergi Chopard, 1925: 9 .

Nemobius larapinthae [sic] – Kirby 1906: 16.

Pteronemobius truncatus – Chopard 1951: 427. — Otte & Alexander 1983: 167–169, figs 124, 128–129, 130a–b, 132b, s. — Baehr 1989: 19. — Messenger 1991: 22. — Hollier et al. 2013: 528 . — Rentz & Su 2019: 339–340.

Diagnosis

A medium- to large-sized ground cricket (body length 6 to 9 mm), coloured brown. Legs with four subapical spurs on both inner and outer edge of Tibia III in both males and females; fourth inner subapical spur is glandular in males. Male forewing light brown in colour, shiny; it reflects light like a mirror ( Fig. 8A–B ); stridulatory file with 97 to 110 teeth. Female forewing has both short ( Fig. 28B ) and long ( Fig. 28C ) morphs; individuals with fully developed hindwings are common.

Etymology

Latin, ‘ truncatus ’ (adj. perf. inf. of ‘ trunco ’) means ‘maimed’, ‘mutilated’. No explanation for the name was given in Saussure (1877).

Material examined (see also Supp. file 1: Table S6 )

Holotype

AUSTRALIA • ♀, adult; 1847; J. Verraux leg.; MNHN EO-ENSIF10379 .

Paratypes

AUSTRALIA • 1 ♀; Queensland, Alice River ; E. Mjöberg leg.; MNHN EO-ENSIF10381 • 1 ♂; Queensland, Malanda ; E. Mjöberg leg.; MNHN EO-ENSIF10382 .

Other material

NEW ZEALAND – Nelson (NN) • 1 ♀; Kaiteriteri, Tasman Bay ; 41.04248° S, 173.01902° E; 0 m a.s.l.; 18 Mar. 2023; C. Stephens leg.; on beach; photograph only; iNaturalist 152116367. – Wanganui (WI) • 1 ♀; Foxton Beach ; 40.46270° S, 175.22160° E; 10 m a.s.l.; 4 May 2019; M. Pélissié leg.; near pond; MPN OR0029 • 1 ♀; Ashhurst ; 40.28221° S, 175.74729° E; 100 m a.s.l.; 27 Jan. 2023; G. Smith leg.; in house porch; photograph only; iNaturalist 147712667. – Taupō (TO) • 1 ♂; Lake Rotopounamu ; 39.02648° S, 175.7308° E; 715 m a.s.l.; 30 Mar. 2019; M. Pélissié leg.; on lake shore; MPN OR0023 . – Taranaki (TK) • 2 ♂♂, 1 ♀; Bell Block, New Plymouth ; 39.02314° S, 174.14505° E; 20 m a.s.l.; 30–31 Mar. 2022; D. Hegg leg.; in lawn near pond; insect net at night; MPN OR0199 to OR0201 • 1 ♀; Awakino Gorge ; 38.62087° S, 174.74416° E; 130 m a.s.l.; 19 Mar. 2024; D. Hegg leg.; in lawn; trowel and jar; MPN OR0324 . – Waikato (WO) • 1 ♀; Manganui Road, Awakino ; 38.61659° S, 174.67720° E; 50 m a.s.l.; 29 Mar. 2022; D. Hegg; on grassy road verge; insect net; MPN OR218 • 2 ♀♀; Leitchs Clearing, Herangi Range ; 38.43453° S, 174.76800° E; 270 m a.s.l.; 2 Apr. 2022; D. Hegg leg.; in tall grass; trowel and jar; MPN OR0219 , OR0220 • 4 ♂♂, 12 ♀♀; Top10 Holiday Park , Cambridge; 37.90592° S, 175.47985° E; 60 m a.s.l.; 13–14 Mar. 2022; D. Hegg leg.; in men’s bathroom; jar; MPN OR0202 to OR0217 • 2 ♂♂, 3 ♀♀; same data as for preceding; 24 Mar. 2024; MPN OR0344 to OR0348 • 1 ♀; Leitchs Hut, Herangi Range ; 38.43333° S, 174.77956° E; 250 m a.s.l.; 21 Mar. 2024; D. Hegg leg.; in tall grass; trowel and jar; MPN OR0335 • 1 ♂; Mangatoa Saddle ; 38.41638° S, 174.72193° E; 300 m a.s.l.; 22 Mar. 2024; D. Hegg leg.; dry dirt in car park; trowel and jar; MPN OR0336 . – Bay of Plenty (BP) • 1 ♂, 1 ♀; Hurunui Hut, Kaimai Range ; 37.81712° S, 175.92802° E; 540 m a.s.l.; 15–16 Apr. 2023; D. Hegg leg.; next to stream; insect net; MPN iNat OR0221 , OR0222 . – Bay of Plenty / Coromandel (BP/ CL) • 1 ♂, 4 ♀♀; Waihi ; 37.38992° S, 175.83290° E; 100 m a.s.l.; 25 Mar. 2024; D. Hegg leg.; in lawn; jar; MPN OR0349 to OR0353 . – Coromandel (CL) • 1 ♀; Coromandel ; 36.76166° S, 175.49129° E; 5 m a.s.l.; 6 Apr. 2024; D. Hegg leg.; in lawn; jar; MPN OR0397 . – Auckland (AK) • 1 ♀; Tahuna Torea Reserve , Auckland; 36.87249° S, 174.88177° E; 0 m a.s.l.; 26 Mar. 2024; D. Hegg leg.; in lawn; jar; MPN OR0354 • 2 ♂♂; Ellerslie Palms Motel , Auckland; 36.89635° S, 174.83458° E; 30 m a.s.l.; 26 Mar. 2024; D. Hegg leg.; in lawn; jar; MPN OR0355 , OR0356 . – Northland (ND) • 1 ♀; Springbank Rd, Kerikeri ; 35.24249° S, 173.92505° E; 100 m a.s.l.; 1 Apr. 2024; D. Hegg leg.; in lawn; jar; MPN OR0386 • 3 ♂♂, 4 ♀♀; Kohuroanaki Loop Track , Te Paki; 34.50864° S, 172.82443° E; 90 m a.s.l.; 4 Dec. 2022; D. Hegg leg.; near water on 4WD track; insect net; MPN OR0191 to OR0198 .

Description

Refer to the detailed description in Otte & Alexander (1983: 167–169). See also Fig. 23 in this work.

MEASUREMENTS. See Table 6 , also Figs 6–7 . No sexual dimorphism.

SONG. A sequence of thrills with a peak frequency between 5.5 kHz and 7 kHz, each thrill up to one and a half seconds in length; interval between thrills between one and three seconds long ( Figs 5 , 24 ; Table 5 ). See also the detailed description in Otte & Alexander (1983: 167–169).

Habitat and ecology

Pteronemobius truncatus is a nocturnal species, almost always found in the proximity of water, including at the edge of ephemeral puddles and in saturated lawns. Swarms of winged individuals are known to form in late summer ( Messenger 1991). Pteronemobius truncatus often forms mixed populations with the smaller Pteronemobius cf. arima and with ground crickets in the genus Bobilla , with which it could easily be confused.

Distribution

Native of Australia, where it is found in all coastal regions, except in the south-west ( Rentz & Su 2019). New Zealand: relatively common in much of North Island; recently also found in the Nelson Region, South Island ( Fig. 38E ). Geographic range expanding southwards.

Figures

Fig. 5. Comparing the song of Pteronemobius truncatus (Saussure, 1877) and of P. tarrios Otte & Alexander, 1983. Data from Otte & Alexander (1983) and from this study. A. Pulse rate as a function of air temperature. B. Peak frequency as a function of air temperature.

Fig. 6. Morphometric measurements for the New Zealand species of Pteronemobius Jacobson, 1904. This figure replicates Otte & Alexander (1983: fig. 129). Measurements for the Australian specimens of P. truncatus (Saussure, 1877) and of P. arima Otte & Alexander, 1983 were extracted from Otte & Alexander (1983). Measurements for the New Zealand specimens of P. truncatus and of P. cf. arima are from the materials examined in this study. A. Relationship between pronotum length and hind femur length in males of Pteronemobius (Otte & Alexander 1983: fig. 129a–b). B. Relationship between ovipositor length and hind femur length in females of Pteronemobius (Otte & Alexander 1983: fig. 129c).

Fig. 7. Morphometric measurements for the New Zealand species of Pteronemobius Jacobson, 1904. In all graphs, orange shapes indicate P. cf. arima Otte & Alexander, 1983; yellow shapes indicate P. truncatus (Saussure, 1877). Both sexes are included unless stated otherwise. A. Boxplot of the ratio of the short and long diagonals in the right male forewing’s posterior cell of the harp (see Fig. 1B). The whiskers include the minimum and maximum values. B. Stridulatory file in male cricket’s right forewing. C. Dimensions of male cricket’s right forewing (Fig. 1B). D. Body length vs ovipositor length (Fig. 1D). E. Major vs minor axis of tympanum (Fig. 1E). For each cricket, the measurements of both left and right tympana are included. F. Length of middle vs dorsal inner apical spurs on tibia III (Fig. 1A).

Fig. 8. Dorsal view of the right forewing in the New Zealand species of Pteronemobius Jacobson, 1904. A–B. Pteronemobius truncatus (Saussure, 1877). A. Drawing from Otte & Alexander (1983: fig. 132b). B. Kohuroanaki Loop Track, Te Paki (MPN OR0197). C. Pteronemobius arima Otte & Alexander, 1983. Drawing from Otte & Alexander (1983: fig. 132m). D. Pteronemobius cf. arima Otte & Alexander, 1983. Maitai Bay, Karikari Peninsula, Northland (MPN OR0246). Scale bars = 1 mm.

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. 24. Pteronemobius truncatus (Saussure, 1877) song, recorded in the field at 24°C. Mangonui, Northland. A. Spectrogram of a sequence of five thrills. B. Oscillogram of a sequence of five thrills. C. Oscillogram of one thrill consisting of 48 pulses. D. Power spectrum of one thrill.

Fig. 27. Pteronemobius Jacobson, 1904, ♂ genitalia of New Zealand species. A–F. Pteronemobius truncatus (Saussure, 1877). Cambridge, Waikato. A–C. Microscope images of pseudepiphallic sclerite (MPNOR0344).A. Dorsal view.B. Ventralview.C. Lateral view.D–F. Micro CT scans,Volume Blending (MPN OR0345). D. Dorsal view. E. Ventral view, cross-section. F. Dorso-lateral view (45º angle). G–L. Pteronemobius cf. arima Otte & Alexander, 1983. G–H. Microscope images of pseudepiphallic sclerite. Maitai Bay, Northland (MPN OR0359). G. Dorsal view. H. Ventral view. I–L. Micro CT scans, Volume Blending. Kerikeri, Northland (MPN OR0385). I. Lateral view. J–K. Dorsal view. L. Dorsolateral view (45º angle). Scale bars = 250 μm.

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. 38. Map of New Zealand, showing the known distribution of taxa included in this study. Thin black lines indicate the boundaries of Crosby’s entomological regions (Crosby et al. 1998; Fig. 2). Coloured circles indicate the collection localities for the material examined.