Small crickets of New Zealand (Orthoptera: Grylloidea: Trigonidiidae and Mogoplistidae), with the description of two new genera and species Hegg, Danilo European Journal of Taxonomy 2024 2024-09-09 955 1 1 87 8NNCL Otte & Alexander, 1983 Otte & Alexander 1983 [747,1161,917,946] Insecta Trigonidiidae Bobilla Animalia Orthoptera 8 9 Arthropoda genus  Out of 368 crickets examined, 138 belong to the genus  Bobilla. These include 69  Bobilla bigelowi, 65  Bobilla nigrovaand 4 specimensfrom the southern Waikato regionthat seem to fall in between the two species. A careful examination of this material supports five out of six of the differences between the two species of  Bobillahighlighted by Swan (1972); these differences are reported in Table 1. In addition to these, Swan (1972)had suggested the number of large bristles on each side of the suranal plate in adult females as a useful trait to differentiate between species ( 2 to 5 in  B. nigrova; 6 to 10 in  Bobilla bigelowi). These bristles however are prone to rubbing off, and their number seems to be more variable than indicated by Swan. I suggest that there is little merit in referring to this trait when identifying  Bobillato species level; I have therefore omitted it from the summary in Table 1. Tooth count in the stridulatory file and song analysis yield numbers that are generally in good agreement with the values reported by McIntyre (1977a)(see Tables 1–2). Male crickets are reliably identified to species level by the number of teeth in the stridulatory file ( Fig. 3B); this however requires removing the insect’s right forewing. The songs of the two species of  Bobilladiffer mainly in their pulse rate, which is around 10 pulses / s in  B. nigrova, around 20 pulses / s in  B. bigelowi( Table 2; Figs 11, 14). The analysis of  Bobillasongs recorded in the field, however, can be difficult; this is explained in detail in this paper’s discussion. In addition to the differences already identified by Swan (1972)and by McIntyre (1977a, 1977b), here I report four more measurements that are significantly different between the two New Zealandspecies of  Bobilla( Table 1). The first one is the ratio of the short and long diagonals in the right male forewing’s posterior cell of the harp (see Figs 1B, 3A). This ratio PCSD /PCLD is greater than 0.49 in  B. bigelowi, less than 0.49 in  B. nigrova(Mainland New Zealandonly, not including Chatham Islands). The measurements for the two species do not overlap, making this a reliable and not destructive method to differentiate between male  B. nigrovaand  B. bigelowibased on their forewings. The second measurement is the ratio between the maximum eye length and the intraocular distance, in a dorsal view of the head (see Figs 1C, 3C). The ratio EL/IOD is greater than 0.79 in  B. bigelowiand less than 0.8 in  B. nigrova, with only a small range of values where the two species overlap. The third difference lies in the width of the tympanal openings on the posterior surface of tibia I. While the length of the tympana is the same in the two species,  B. bigelowihas narrower openings ( Fig. 3E). The fourth measurement is the length ratio of the middle vs dorsal inner apical spurs on tibia III, which is around 0.9 in  B. nigrova, 0.8 in  B. bigelowi(see Figs 3F, 4). While the width of the tympana and the length of the apical spurs on tibia III differ significantly between species ( Table 1), there is too much overlap in their ranges to rely on these measurements for the purpose of species identification.   Table 1.Genus  Bobilla Otte & Alexander, 1983. Summary of morphological differences between adults of the two New Zealand species,  Bobilla nigrova( Swan, 1972)and  Bobilla bigelowi( Swan, 1972). All abbreviations used here are explained in the Material and methods section. All counts and measurements are median values, followed by minimum and maximum values in brackets. Nindicates the sample size.     Morphological trait    Bobilla nigrova( Swan, 1972)    Bobilla bigelowi( Swan, 1972)  t-test result  Figures   Males  Spike-like tufts of bristles on each side of the suranal plate ( Swan 1972). present absent Fig. 10A Fig. 11D  Ratio PCSD / PCLD Mainland NZ only 0.478 (0.438–0.488) N= 13 0.522 (0.496–0.558) N= 30  p<10-10 Fig. 1B Fig. 3A  Number of teeth in stridulatory file (McIntyre 1977) (188–283) N= 85 (123–190) N= 83  Number of teeth in stridulatory file (this study) 204 (180–246) N= 11 152 (118–171) N= 30  p<10-12 Fig. 3B  Song: pulse rate (pulses / s) (McIntyre 1977) 13 (11–15) N= 36 21 (20–22) N= 61 Fig. 12 Fig. 15  Song: Main frequency (McIntyre 1977) 8.0 kHz at 27°C 7.5 kHz 27°C Fig. 12 Fig. 15   Females  Dorsal surface of abdomen ( Swan 1972) grey or black, with pale markings uniform black Fig. 10B Fig. 13B  Lateral valves of ovipositor ( Swan 1972) strongly denticulate weakly denticulate Fig. 11G–H Fig. 14F–G  Egg colour ( Swan 1972) black pale Fig. 11F Fig. 14E  Ovipositor length (mm) ( Swan 1972) long (mean 4.9 mm)1 short (mean 4.1 mm) Fig. 3D  Ovipositor length (mm) (this study) 5.9 (4.0–6.7) N= 20 4.0 (3.1–4.9) N= 26  p<10-13 Fig. 3D   Both sexes  Ratio eye length / intraocular distance 0.754 (0.705–0.806) N= 18 0.840 (0.789–0.901) N= 37  p<10-16 Fig. 1C Fig. 3C  Minor axis of tympanum (µm) 119 (105–154) N= 32 95 (67–122) N= 76  p<10-6 Fig. 1E Fig. 3E  Length ratio of middle and dorsal inner spurs at apex of tibia III 0.882 (0.833–0.959) N= 18 0.822 (0.744–0.912) N= 38   p<10-5 Fig. 3F   1Note the discrepancy between Swan’s and this study’s measurements. After re-measuring Swan’s paratypes( N= 40) I calculated a mean ovipositor length of 5.3 mmin  B. nigrova.   Table 2(continued on next page). Adult male and female measurements in the New Zealand species of  Bobilla Otte & Alexander, 1983. All abbreviations used here are explained in the Material and methods section. All counts and measurements are median values, followed by minimum and maximum values in brackets. Nindicates the sample size.     Measurement    Bobilla nigrova( Swan, 1972)    Bobilla bigelowi( Swan, 1972)   male  female  male  female  Body length (mm) 6.6 (5.9–7.1) N= 11 8.1 (5.6–9.6) N= 19 6.2 (5.4–7.2) N= 30 6.7 (5.3–8.6) N= 28  Pronotum width (mm) 2.0 (1.9–2.2) N= 9 2.3 (1.8–2.7) N= 15 2.0 (1.7–2.1) N= 27 2.0 (1.6–2.4) N= 22  Pronotum length (mm) 1.3 (1.1–1.4) N= 9 1.5 (1.3–1.6) N= 15 1.2 (1.1–1.9) N= 22 1.4 (1.1–2.0) N= 27  Femur III length (mm) 4.8 (4.6–4.9) N= 6 5.6 (4.9–6.1) N= 12 4.6 (4.2–5.0) N= 22 5.0 (4.4–5.6) N= 18  Tibia III length (mm) 3.7 (3.5–4.2) N= 6 4.4 (3.8–5.2) N= 12 3.6 (3.3–4.1) N= 22 4.0 (3.4–4.7) N= 18  Number of subapical spurs on TIII inner 3 3 3 3  Number of subapical spurs on TIII outer 3 3 3 3  Ovipositor length (mm) – 5.9 (4.0–6.7) N= 20 – 4.0 (3.1–4.9) N= 26  EL / IOD 0.77 (0.71–0.77) N= 6 0.75 (0.72–0.81) N= 12 0.84 (0.80–0.90) N= 20 0.84 (0.79–0.88) N= 17  Short FW Wing Long FW morphs Fully winged – 17 – 16  8 2 25 6  0 2 2 0  FWW (mm) 2.2 (2.1–2.4) N= 7 1.5 (1.3–1.8) N= 12 2.0 (1.9–2.4) N= 25 1.3 (0.9–1.6) N= 18  FWL (mm) 3.2 (2.9–3.6) N= 8 Short 2.5 (1.7–3.1) Long 4.7 (4.6–4.8) 3.1 (2.5–3.7) N= 27 Short 2.1 (1.5–2.7) Long 3.9 (3.6–4.2)  HWL (mm) – – 8.0 (8.0–8.0) N= 2 –  PCSD / PCLD (Mainland NZ only) 0.478 (0.438–0.488) N= 13 – 0.522 (0.496–0.558) N= 30 –  ST 204 (180–246) N= 11 – 152 (118–171) N= 30 –  SFL (µm) 1354 (1284–1554) N= 6 – 1265 (944–1384) N= 8 –  tmao / tmai 0.59 (0.52–0.65) N= 6 0.61 (0.54–0.69) N= 11 0.66 (0.59–0.72) N= 20 0.64 (0.56–0.74) N= 17  tao1 / tai1 0.97 (0.88–1.07) N= 6 0.99 (0.78–1.08) N= 12 0.98 (0.82–1.12) N= 20 0.94 (0.81–1.08) N= 18   Table 2(continued). Adult male and female measurements in the New Zealand species of  Bobilla Otte & Alexander, 1983. All abbreviations used here are explained in the Material and methods section. All counts and measurements are median values, followed by minimum and maximum values in brackets. Nindicates the sample size.     Measurement    Bobilla nigrova( Swan, 1972)    Bobilla bigelowi( Swan, 1972)  male  female male  female  Song (21°C) Song (22°C)  Peak frequency (kHz) 8.1 – 7.9 –  Pulse duration (ms) 33 – 24 –  Pulse interval (ms) 69 – 23 –  Pulse rate (pulses/s) 10.1 – 20.3 –  Chirp duration (s) 0.4–0.7 – 0.5–0.6 –  Chirp interval (s) 0.4–0.6 – 0.2–0.3 –  Nine specimensof  Bobillacollected on Pitt Island (Chathams), 800 kmeast of New Zealand, all fit the description of  B. nigrovain their morphology, song, and male genitalia. The mean ratio PCSD / PCLD, however, is 0.511 (min 0.493, max 0.576, N= 5), typical of  B. bigelowion mainland New Zealand. This suggests that the  Bobillapopulation on Chatham Islandsmay have been isolated for some time.  Two adultmale  Bobilla bigelowicollected at Lake Ōhau, Mackenzie Country, had fully developed hindwings ( Fig. 12A). This contradicts Swan’s (1972)statement that “[  Bobilla bigelowi] males are always apterous, but macropterous females with hindwings extending beyond the tip of the ovipositor are not uncommon (3–6 percent of a population)”. Fully winged specimens occur in both sexes and in both species but are rare. Of interest is a population in the southern Waikato region, where nine out of twelve femalespecimens of  Bobillacollected had long forewings, the remaining three having short forewings. This contrasts with 1 out of 16  B. bigelowiwith long forewings and 1 out of 14  B. nigrovawith long forewings from the rest of the country, the morph with short forewings being by far the most common in both species. Four of the specimens from this southern Waikato regioncould not be assigned with certainty to either of the two species; rather, they seem to fall in between. Females have the dark colour and white eggs of  B. bigelowi, but the long ovipositor with denticulate lateral valves of  B. nigrova. The number of teeth in the stridulatory file and the ratio of eye length over intraocular distance lye half-way between the typical ranges for the two species. It seems most likely that this would be a hybrid population arising from interbreeding between the two species of  Bobilla. For more information about the origin of these specimens, see Supp. file 1: Table S3.   Silent ground crickets Out of 368 crickets examined, 41 are ground crickets (subfamily Nemobiinae) lacking a stridulatory apparatus or tympana and belonging to two clearly distinct taxa, one from the forests of New Zealand’s South Island and from Mt Ruapehu, the other one exclusively from North Island. No silent ground crickets have previously been described from New Zealand. Several genera of silent nemobiine crickets have been described from other regions in the Southern hemisphere. These include seven genera from Australia( Rentz & Su 2019: 319):  Narellina Otte, 1994;  Eumarinemobius Gorochov & Tan, 2018;  Tincanita Otte &Alexander, 1983;  Silvinella Otte &Alexander, 1983;  Nambungia Otte & Alexander, 1983;  TerritirritiaRentz & Su, 1996; and  CalperumRentz & Su, 1996; six genera from South America:  AbsonemobiusDesutter-Grandcolas, 1993;  PhoremiaDesutter-Grandcolas, 1993;  Amanayarade Mello & Jacomini, 1994;  Monopteropsisde Mello & Jacomini, 1994;  KevanemobiusBolfarini & de Mello, 2012; and  Pepoapua Jesus & Pereira, 2017; one genus from Vanuatuand Samoa(Desutter-Grandcolas 2009):  CophonemobiusChopard, 1929; three genera from New Caledonia( Anso et al.2016; Desutter-Grandcolas et al. 2016):  Paniella Otte, Alexander & Cade, 1987;  OrintiaGorochov, 1986; and  KanakinemobiusDesutter-Grandcolas, 2016. The two New Zealandtaxa have been carefully compared with descriptions and photographs of all of the above genera ( Table 3), and don’t match any of these. The southern taxon is apterous in both males and females and has characteristic male genitalia with articulated pseudepiphallic parameres, modified for clasping. While it looks deceptively similar to  Absonemobiusin photograph, the latter genus has a head that is wider than it is high in frontal view (Desutter-Grandcolas 1993) and macroscopically different male genitalia (see Desutter-Grandcolas & Hugel 2016). Among Australian genera, it most resembles  TerritirritiaRentz & Su, 1996, but has a different number of sub-apical spines on the hind tibiae and again different male genitalia. Here, the southern species is assigned to a new monotypic genus,  Austronemobius gen. nov. The northern taxon is noticeably larger and has reduced forewings that look identical in males and females, without a stridulatory apparatus in males. While superficially similar to New Caledonia’s  Kanakinemobius, the structure of the male forewings places it in a separate genus. The male genitalia of the northern taxon resemble those of  Amanayarafrom South America, but the latter genus is entirely apterous and has two glandular subapical spurs on the inner side of the hind tibia in males (de Mello & Jacomini 1994). The structure of the wings closely resembles that of the South American genus  Pepoapua, but the latter genus has different male genitalia and a serrated ovipositor in females ( Jesus et al.2017). Here, the northern taxon is assigned to a new monotypic genus,  Mutonemobius gen. nov.   Table 3.Comparison of different genera of silent nemobiine crickets in the Southern hemisphere by morphology (after Rentz & Su 2019: table 8).    Genus  Auditory tympanum  Forewings  SF  Ovipositor tip  Subapical spurs on Tibia III  ♂ ♀ ♂ ♀ ♂ ♀ ♂ ♀  Ant. Post. Ant. Post. i. o. i. o.   New Zealand    Austronemobius gen. nov. – – – – – – – Tuberculated 3 3 3 3    Mutonemobius gen. nov. – – – – + + – Smooth 4 3,4a 4 3,4a   Australia    Calperum – – – – – – – Serrated 3 3 3 3    Eumarinemobius – – – – – – – Smooth 2 3 2 3    Nambungia – – – – – – – Smooth 3 3 3 3    Narellina – – – – + + – Serrated 4 3 4 3    Silvinella – – – – – – – Smooth 3 3 3 3    Territirritia – – – – – – – Serrated 2 2 2 2    Tincanita – – – – + – – Smooth 3 3 3 3   Vanuatu and Samoa    Cophonemobius – – – – + + – Smooth 3 3 3 3   New Caledonia    Kanakinemobius – – – – + + + Smooth 4 4 4 4    Orintia – + – + – – – Serrated 3 3 3 3    Paniella – – – – – – – Serrated 3 3 3 3   South America    Absonemobius – – – – – – – Smooth or serrated b 3,4b 3,4b 3,4b 3,4b    Amanayara – – – – – – – Serrated 4 3 3 3    Kevanemobius – – – – + + – Serrated 4 4 4 4    Monopteropsis – – – – + – + Smooth 4 3 4 3    Pepoapua – – – – + + – Serrated 4 3 4 3    Phoremia – – – – – – – Serrated 3 3 3 3   aindividual variation within species and population.  bvaries between species.   Table 4.Adult male and female measurements in the New Zealand species of silent Nemobiinae Saussure, 1877. All abbreviations used here are explained in the Material and methods section. All counts and measurements are median values, followed by minimum and maximum values in brackets. Nindicates the sample size.     Measurement   Austronemobius chelatus gen. et sp. nov.   Mutonemobius marmoratus gen. et sp. nov.   male  female  male  female  Body length (mm) 6.4 (5.4–8.3) N= 4 6.2 (5.8–7.9) N= 5 7.3 (7.0–8.4) N= 7 8.3 (7.6–9.2) N= 16  Pronotum width (mm) 1.7 (1.6–1.9) N= 4 1.9 (1.8–2.1) N= 5 2.3 (2.0–2.4) N= 7 2.4 (2.2–2.7) N= 16  Pronotum length (mm) 1.3 (1.2–1.4) N= 4 1.5 (1.4–1.7) N= 5 1.7 (1.5–1.9) N= 7 1.8 (1.6–2.0) N= 16  Femur III length (mm) 4.1 (3.9–4.2) N= 4 4.4 (4.1–4.6) N= 4 5.1 (4.5–5.7) N= 7 5.5 (5.1–5.8) N= 15  Tibia III length (mm) 2.8 (2.7–2.9) N= 4 3.0 (2.9–3.0) N= 4 3.6 (3.1–4.1) N= 6 3.8 (3.6–4.2) N= 15  Number of subapical spurs on TIII inner 3 3 4 4  Number of subapical spurs on TIII outer 3 3 3 ( N= 6 out of 7) 4 ( N= 1 out of 7) 3 ( N= 14 out of 16) 4 ( N= 2 out of 16)  Ovipositor length (mm) – 2.9 (2.6–3.1) N= 5 – 4.9 (4.5–5.6) N= 14  OL / BL – 0.45 (0.40–0.50) N= 5 – 0.59 (0.54–0.66) N= 14  FWW (mm) – – 1.3 (1.1–1.5) N= 7 1.4 (1.1–1.6) N= 16  FWL (mm) – – 0.8 (0.7–1.2) N= 7 0.7 (0.6–1.1) N= 16  tmao / tmai 0.80 (0.48–0.94) N= 4 0.86 (0.68–0.92) N= 4 0.69 (0.62–0.72) N= 5 0.73 (0.66–0.81) N= 15  tao1 / tai1 0.85 (0.79–0.87) N= 4 0.90 (0.83–0.99) N= 4 0.80 (0.75–0.97) N= 6 0.84 (0.75–0.96) N= 15   Table 5.Parameters of  Pteronemobius truncatus( Saussure, 1877)song at different localities and temperatures.     Locality  Air Temperature [°C]  Ground Temperature [°C]  Peak Frequency [kHz]  Pulse Rate [p/s]  Pulse Duration [ms]  Pulse Interval [ms]  Chirp Duration [s]  Chirp Interval [s]  Mangonui 20.4 10.4 5.6 49.2 14.7 5.5 0.6–0.7 1.9–3.3  Mangonui 24.0 22.0 6.6 51.6 14.4 4.6 0.9–1.1 0.7–1.1  Te Paki 16.8 13.0 5.6 42.7 16.4 6.8 1.1–1.4 1.5–1.9  Te Paki 13.8 13.0 5.4 39.8 16.3 9.3 1.2–1.5 2.0–2.4 Both new genera,  Austronemobius gen. nov.and  Mutonemobius gen. nov., are placed in the tribe Nemobiini Vickery, 1973based on the absence of a glandular subapical spur on the inner edge of Tibia III in males ( Vickery 1973).