Pterapotrechus salomonoides
Creators: name: Hegg, Danilo
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Orthoptera
Gryllacrididae
Pterapotrechus
Pterapotrechus salomonoides

description: Pterapotrechus salomonoides (Karny, 1929)
Figs 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13
Paragryllacris salomonoides Karny, 1929: 14.
Pterapotrechus salomonoides — Karny 1937: 73. — Cadena-Castañeda 2019: 99.
Diagnosis. —
P. salomonoides is the smaller of the two species in the genus Pterapotrechus (Fig. 4). Body usually shorter than 30 mm. Tegmina always shorter than 30 mm. Ovipositor short (<20 mm) and strongly recurved upwards (Fig. 9 F). Frons black (Fig. 6 B). Female subgenital plate bilobed (Fig. 9 E). Male subgenital plate triangular, bearing numerous dense, stout spinules on the median keel underneath (Fig. 9 B, C).
Habitat and distribution. —
Coastal forests in southern Queensland and northern New South Wales, Australia. Introduced by anthropogenic means and naturalized in North Island, New Zealand.
Etymology. —
Named for its resemblance to katydids in the genus Salomona Blanchard, 1853 (Karny 1929). ‘ Salomonoides ’ is an adjective of the third declension.
Material examined. —
(See also Suppl. material 1: table S 1) Holotype: AUSTRALIA • ♀; Queensland, Tamborine Mountain; 27.9°S, 153.2°E; 500 m. a. s. l.; 1910–1913; E. Mjöberg leg.; NRM ORTH 0000231.
Representative male: AUSTRALIA • 1 ♂; Queensland, Tamborine Mountain, MacDonald Rainforest Circuit; 27.91845°S, 153.20455°E; 500 m. a. s. l.; 15 Nov. 2023; D. Hegg leg.; rainforest, in foliage; insect net; QM T 260852.
Other material. AUSTRALIA – Queensland (QLD) • 1 ♀; Tamborine Mountain, MacDonald Rainforest Circuit; 27.91845°S, 153.20455°E; 500 m. a. s. l.; 15 Nov. 2023; D. Hegg leg.; rainforest, in foliage; insect net; GenBank: PP 971680; MPN OR 0548 • 1 ♀; Tamborine Mountain, Esme Lahey Environmental Park; 27.94776°S, 153.19386°E; 530 m. a. s. l.; 13 Nov. 2023; D. Hegg leg.; rainforest, in foliage; insect net; GenBank: PP 971677; MPN OR 0546 • 1 ♂; same collection data as for preceding; MPN OR 0547 • 1 ♂; Springbrook NP, Purling Brook Falls; 28.18950°S, 153.27177°E; 600 m. a. s. l.; 18 Nov. 2023; D. Hegg leg.; in park map display case; insect net; GenBank: PP 971678; MPN OR 0543 • 1 ♂; same collection data as for preceding; MPN OR 0549 • 1 ♀; Binna Burra; 28.19925°S, 153.18819°E; 820 m. a. s. l.; 14 Nov. 2023; Rainforest, D. Hegg leg.; rainforest, in foliage; insect net; GenBank: PP 971679; MPN OR 0544 • 1 ♂; same collection data as for preceding; MPN OR 0545. NEW ZEALAND – Auckland (AK) • Helensville, Mangakura Road; 36.69°S, 174.45°E; 20 m. a. s. l.; 13 Jan. 2021; N. Clayton leg.; inside house; jar; MPN OR 0440 • 4 ♂♂, 1 ♀; Tahuna Torea Reserve; 36.87169°S, 174.88205°E; 0 m. a. s. l.; 23 Nov. 2023; D. Hegg leg.; native forest, in foliage; insect net; MPN OR 0535 to OR 0538, OR 0533 • 1 ♀; same collection data as for preceding; GenBank: PP 971675; MPN OR 0544. – Northland (ND) • 1 ♂; Kerikeri; 35.21570°S, 173.96044°E; 20 m. a. s. l.; 21 Nov. 2021; D. Hegg leg.; native forest, in foliage; insect net; MPN OR 0541 • 1 ♂; Kerikeri; 35.21797°S, 173.95276°E; 20 m. a. s. l.; 29 Nov. 2021; D. Hegg leg.; native forest, in foliage; insect net; MPN OR 0539 • 1 ♀; Kerikeri; 35.21649°S, 173.96051°E; 20 m. a. s. l.; 13 Dec. 2022; native forest, in foliage; insect net; MPN OR 0540 • 1 ♀; same collection data as for preceding; GenBank: PP 971676; MPN OR 0542.
Description. —
Karny’s (1929) original description of the species (see Suppl. material 1: appendix A) is for the adult female only. The male was never described. While Karny’s description is minutiously accurate, it is wordy and hard to follow with few illustrations. Curiously, it lacks any mention of the stridulatory apparatus, which in Gryllacrididae is present in both males and females.
A new description of the species is given here, based on the examination of 19 fresh specimens, and including a description of the male for the first time.
Measurements. See Table 1. Females tend to be slightly larger than males, but not significantly so.
Head. (Fig. 6 A, B). No noticeable sexual dimorphism. Vertex heavily domed, glabrous, smooth, and shiny, pale. Median ocellum visible as a white dot. Just below the ocellum, a shallow V-shaped line separates the pale fastigium from the black frons. The latter is wrinkled throughout and is delimited on the sides by prominent ridges running from the insertions of the antennae to the base of the mandible; these ridges are diagnostic of the genus Pterapotrechus. Mandibles very strong, sharp. Labrum and mandibles dark red / brown. Labial and maxillary palpi pale. Antennae uniform brown, very long, four times the body length or more.
Thorax. Pronotum pale; reddish-brown only near the margins. Anterior margin convex in the middle; posterior margin straight. Anterior corners of the lateral lobes in the shape of sharp right angles; posterior corners truncated. A straight median sulcus and two curved sulci on either side of the pronotal discus give the pronotum a characteristic dorsal pattern (Fig. 6 D). Dark markings on parts of the sulci are often present but not in all individuals.
Wings. (Fig. 7). Fore- and hindwings well developed in adult males and females. Forewings truncated in apical half, shaped like the blade of a kayak paddle; shorter than body, yet always reaching beyond the end of the abdomen; falling well short of the apex of the ovipositor in females (Fig. 10 B). Hindwings on average 6 % longer than the forewings. Wing shape as in Chauliogryllacris acaropenates Rentz et al., 2018 and in Béthoux 2012: Fig. 16. Wing venation simpler than in most other Australian Gryllacrididae (Béthoux 2012), with veins CuA, CuPaα, and CuPaβ fused into a single vein in both forewing and hindwing. Veins MA and MP share the basal stem with RP in the hindwings.
Legs. Fore and mid femora approximately one-third of body length, unarmed. Fore and mid tibiae hairy above; armed ventrally with one pair of spines at the apex (Fig. 6 F) and with four pairs of strong, sharp spurs that are articulated at the base (Fig. 6 F; detail in Fig. 6 C). Hind femora smooth inside, but with a scabrous stridulatory file near the dorsal edge in basal third (Fig. 8 C, D); armed ventrally in distal half often but not always with one spine on inner edge, always with two to four spines on outer edge. Hind tibiae hairy above, unarmed in basal half (Fig. 6 G); armed ventrally with one pair of spines near the apex; armed dorsally on both sides with two to four spines in distal half (Fig. 6 G). Hind tibiae armed with three pairs of apical spurs, one dorsal and two ventral, the ventral spurs being recurved upwards.
Abdomen. Shape typical of other Gryllacrididae, with two rows of stridulatory pegs laterally on both tergites T 2 and T 3 (Fig. 8 A, B). Peg counts in all four rows are reported in Table 1.
Male terminalia. Internal male genitalia soft, non-sclerotized, as in most other Australian Gryllacrididae (Rentz and John 1990, Rentz et al. 2018). Suranal plate pale, roughly trapezoidal, with two very prominent, darkened, cat’s ear-shaped lobes on the apical vertices (Fig. 9 A). Subgenital plate triangular, bearing numerous dense, stout spinules on the median keel underneath (Fig. 9 B, C).
Female terminalia. Subgenital plate glabrous, with two pointed lobes giving it the shape of a capital letter M (Fig. 9 E). Ovipositor on average 60 % of body length, strongly recurved upwards (Fig. 9 F).
Eggs. One female from Kerikeri, New Zealand (MPN OR 0540) was dissected and found to be carrying 62 eggs in various stages of development. Mature eggs are yellow, elongated, between 4 mm and 4.5 mm long and approx. 1.5 mm wide at center (Fig. 9 G).
Geographic distribution in New Zealand. —
As of mid- 2024, the known geographic distribution of Pterapotrechus salomonoides (Karny, 1929) in New Zealand is centered around Auckland (36.9°S, 174.8°E) and extends northwards to Cable Bay, Northland (35.0°S, 173.5°E) and southwards to a line joining Raglan, Hamilton, and Tauranga (Latitude 37.5°S) (Fig. 11).
A total of 436 observations of Pterapotrechus salomonoides in New Zealand were recorded in the iNaturalist (https://www.inaturalist.org) database from 1 July 2012 to 30 June 2024. Ten of these observations were discarded for having obscured or private coordinates that could not be obtained. The remaining 426 observations are mapped in Fig. 11. Two observations from this dataset were removed from the subsequent numerical analysis of the insect’s geographic distribution, since they appear to be outliers, and it could not be confirmed that a population has actually established at either of these locations. The observations discarded, shown as yellow dots in Fig. 11, are from Te Kaha, Bay of Plenty, in October 2021 (iNaturalist 96763859), with coordinates that are possibly inaccurate, and from Taupō in July 2022 (iNaturalist 178798045). The insect in the latter observation was found in a campervan and had possibly just traveled from a different location.
The maximum diameter of the species’ geographic range in New Zealand has been increasing steadily since 2012 (Fig. 12 A). A straight line with a slope of 36.96 km / year is a good fit for the observed data (R 2 = 0.94), indicating that the insect has been advancing at an average of 18.5 km per year in all directions.
The increase in land area occupied by the species’ geographic range (Fig. 12 B) is best approximated by a second order polynomial (R 2 = 0.97), with a coefficient of the quadratic term equal to 271.8 (km / year) 2. If the region occupied by the insect were circular, this would be equivalent to the insect advancing at an average 271. 8 ÷ π = 9. 3 km per year in all directions. The discrepancy between the two numbers calculated here is easily explained by the constraints posed by New Zealand’s geography, which does not lend itself to being approximated with a simple geometrical shape.
Population density in the city of Auckland, New Zealand. —
In the city of Auckland, New Zealand, 352 Pterapotrechus salomonoides (Karny, 1929) observations were recorded on iNaturalist (https://www.inaturalist.org) by 243 individual observers from 1 July 2012 to 30 June 2024. Numbers broken down by year are graphed in Fig. 13.
The total number of P. salomonoides observations in Auckland increased from one per year in 2013 and 2014 to one hundred per year in 2024 (Fig. 13 A). The total number of iNaturalist insect observations in Auckland also increased from 735 per year to 12,160 per year in the same time period. The percentage of P. salomonoides among all insect observations in Auckland increased six-fold from 0.14 % in 2013 to 0.81 % in 2024 (Fig. 13 C).
The number of observers in Auckland who reported at least one P. salomonoides observation increased from one per year in 2013 to 85 per year in 2024 (Fig. 13 B). The number of observers in Auckland who have reported at least one insect observation has also increased from 41 per year to 1,075 per year in the same time period. The percentage of P. salomonoides observers among all observers who have recorded at least one insect in Auckland has increased four-fold from 2.4 % in 2013 to 9.2 % in 2024 (Fig. 13 D).
Dietary observations. —
Pterapotrechus salomonoides specimens held in captivity were omnivores. They readily consumed grated apple and appeared to ignore grated carrot and pet food. They hunted and ate a variety of nocturnal invertebrates including moths, crane flies, and Orthoptera, but seemed unable to detect diurnal Diptera that rest at night.
A list of the food choices offered to the captive Pterapotrechus salomonoides specimens, and whether they were consumed or ignored, is shown in Table 2. Quantities eaten were not recorded.
description: Published as part of Hegg, Danilo, 2025, An Australian raspy cricket established in New Zealand, Pterapotrechus salomonoides (Orthoptera, Gryllacrididae), with notes on ecology and first description of the male, pp. 77-94 in Journal of Orthoptera Research 34 (1) on pages 77-94, DOI: 10.3897/jor.34.134391