Nisitrus Saussure, 1878

Tan, Ming Kai, Wahab, Rodzay bin Haji Abdul, Japir, Razy, Chung, Authur Y. C. & Robillard, Tony, 2021, Revision of the cricket genus Nisitrus Saussure (Orthoptera: Gryllidae: Eneopterinae) and descriptions of five new species, European Journal of Taxonomy 761 (1), pp. 1-75 : 12-25

publication ID	https://doi.org/ 10.5852/ejt.2021.761.1449
publication LSID	lsid:zoobank.org:pub:519E2F56-40E1-4431-BC90-8484E308D16E
DOI	https://doi.org/10.5281/zenodo.5169988
persistent identifier	https://treatment.plazi.org/id/039487A4-FFE7-FFE4-FD84-F13EFAA2FDE3
treatment provided by	Felipe
scientific name	Nisitrus Saussure, 1878
status

Treatment

Genus Nisitrus Saussure, 1878 View in CoL View at ENA

Nisitra Walker, 1869: 91 View in CoL .

Nisitra View in CoL – Chopard 1940: 199.

Nisitrus View in CoL – Saussure 1878: 511, 522 (nomen novum for Nisitra Walker View in CoL ). — Chopard 1968: 352. — Desutter-Grandcolas 1990: 239. — Otte 1994: 67. — Preston-Mafham 2000: 2241 (behaviour). — Robillard & Desutter-Grandcolas 2004a: 276; 2004b: 578; 2004c: 304; 2006: 644; 2008: 67 ( Nisitrini View in CoL tribe); 2011: 637. — Robillard et al. 2007: 1265. — Desutter-Grandcolas et al. 2010: 616. — Nattier et al. 2011: 2201 (phylogeny and molecular dating). — Robillard & Tan 2013: 707 View Cited Treatment (redescription and diagnosis). — Vicente et al. 2017: 2203 (phylogeny, historical biogeography). — Cigliano et al. 2020 ( Orthoptera View in CoL Species File Online).

Type species

Nisitra vittatus ( Haan, 1844) View in CoL .

Remarks on type species

Kirby (1906) and Chopard (1968) listed N. vittata as the type species of Nisitra and treated the original type species N. marginata Walker, 1869 as a synonym of N. vittata . Subsequent authors listed N. vittatus as the type species of the replacement name Nisitrus , although Otte (1994) reinstated N. marginatus as a valid species (Braun 2013 in Cigliano et al. 2020). The present revision revalidates the synonymy of N. marginatus under N. vittatus , making N. vittatus the valid type species of the genus.

Diagnosis (emended from Robillard & Tan 2013)

Among genera of Eneopterinae , Nisitrus is characterised by an elegant, wasp-like, slender and colourful body ( Figs 7–9 View Fig View Fig View Fig ). Size average for subfamily. Colouration vivid, dominantly yellow, whitish and black, with species-specific patterns, particularly in the head ( Figs 10–11 View Fig View Fig ), pronotum ( Figs 11–12 View Fig View Fig ) and FWs ( Figs 12–14 View Fig View Fig View Fig ). Characteristic head shape with narrow fastigium and large prominent eyes with thin dorso-ventral black stripes. Pronotum setose, square-shaped to slightly trapezoidal, usually bisinuated posteriorly. Metanotum with large glandular structures in males, made of a wide pit on scutum and a pair of posterior pits on scutellum, with glandular pores mostly organised by groups of 2 or 3 ( Fig. 15 View Fig ). FWs more or less as long as abdomen. Male Nisitrus show modified FW venation and characteristic glossy transparency. Hindwings longer than FWs, bicoloured in most species, their base transparent with a wide dark posterior margin. Legs long and thin, FIII with a characteristic narrowed area before knee. Other general traits: TI with two tympana, inner one slit-like, covered by a swollen cuticular expansion; outer tympanum oval, its membrane transversally plicate in dorsal half. TI with three apical spurs; outer dorsal spur missing. TII with four apical spurs, inner longest. TIII with three inner and three outer apical spurs, median longest on each side; four pairs of subapical spurs, inner and outer spurs almost straight, their apex hook-like; TIII serrulate over whole length, slightly furrowed dorsally. Tarsomeres III-1 with one row of dorsal spines on external edge in addition to apical spines. Apical claws of legs slightly indented. Both males and females show characteristic genitalia.

Male genitalia ( Fig. 16 View Fig ) with membranous and setose lophi well individualised; pseudepiphallic parameres including two membranous posterior lobes and a sclerotized anterior lobe oriented anteriorly toward median axis of genitalia and carrying a secondary preapical sclerotized lobe; ectophallic arc transverse, incomplete due to a little-sclerotized median area; ectophallic fold narrowed preapically, its apex narrow, located between anterior apex of pseudepiphallic parameres; dorsal part of fold sclerotized, forming two elongated sclerites connected to the median area of arc; ventral part of ectophallic fold membranous, with two strong rounded lateral sclerites of variable shapes. Membrane of endophallic cavity smooth. Female copulatory papilla ( Fig. 17 View Fig ) conical, apex generally sclerotized and pointed. Ovipositor typically longer than FIII; apex thin with both dorsal and ventral edges smooth.

Phylogenetic relationships

Based on previous phylogenetic studies ( Robillard & Desutter-Grandcolas 2004c; Nattier et al. 2011; Vicente et al. 2017), Nisitrus is the sister genus of Paranisitra Chopard, 1925 (revision in Gorochov 2009 and Baroga-Barbecho et al. 2019). The two genera form the Nisitrini tribe ( Robillard & Desutter-Grandcolas 2008) and are very close morphologically; Paranisitra is mostly characterised by a lack of wings in both sexes, but except for this, it shares with Nisitrus its general body shape, long thin legs with indented claws, colouration with yellow and black, head shape with large prominent eyes and narrow fastigium, and the general structure of male and female genitalia. Nisitrini are less easy to relate to other clades of Eneopterinae .

Natural history

Species tend to be found at forest edges and gaps in the forest where the vegetation is more exposed. They are also found among shrubs and herbaceous plants (but not grasses). Nisitrus are observed to be generally diurnal, during which the males can be heard calling and individuals are found foraging in the vegetation. It seems as Nisitrus are mostly herbivorous, feeding on leaves, but also on flowers ( Tan et al. 2017). Nisitrus are also observed to congregate with one another on the same plant, sometimes making up of more than 20 individuals of both adults and nymphs. They can be considered a pest in some parts of Southeast Asia ( Willemse 2001).

Included species

Nisitrus brunnerianus View in CoL from Borneo and Java; N. crucius View in CoL sp. nov. and N. danum View in CoL sp. nov. (both from Borneo); N. hughtani View in CoL sp. nov. from Sumatra; N. hyalinus View in CoL from Borneo; N. insignis View in CoL from Sumatra and Malay Peninsula; N. malaya View in CoL sp. nov. from Malay Peninsula; N. musicus View in CoL and N. rindu View in CoL sp. nov. from Borneo; and N. vittatus View in CoL from Sumatra and Borneo.

Distribution

Borneo (Sabah and Sarawak States of East Malaysia, Brunei Darussalam, and Kalimantan State of Indonesia), Java, Malay Peninsula (Peninsular Malaysia and Singapore) and Sumatra ( Indonesia) ( Fig. 5 View Fig ).

Key to the species of Nisitrus Saussure, 1878

1. Frons mostly black, or with large dark markings (e.g., cross-shaped pattern); gena usually black, although may have yellow band ventral of eye ................................................................................ 2

– Frons mostly yellow, sometimes with small dots but without large dark markings; gena usually yellow ............................................................................................................................................... 5

2. FW with longitudinal white stripe around region of CuA, M and R with a distinct margin from black colouration on dorsal field; lateral field usually infumated black ventrally. Distribution: Sumatra ................................................................................... N. hughtani Robillard & Tan View in CoL sp. nov.

– FW with longitudinal white stripe around region of CuA, M and R darkens progressively towards the dorsal field without a distinct margin from black colouration on dorsal field; lateral field usually light coloured or transparent ventrally. Distribution: Borneo and Java ............................................ 3

3. Smaller in size, female FWL typically <11.3 mm. Frons with a characteristic black cross marking .................................................................................................... N. crucius Robillard & Tan View in CoL sp. nov.

– Larger in size, female FWL typically> 11.8 mm. Frons completely black; without a characteristic black cross marking .......................................................................................................................... 4

4. Dorsum of head completely black. Pronotal lateral lobe either with ventral half yellow or with an oval yellow spot at the anterior end ................................................ N. brunnerianus Saussure, 1878 View in CoL

– Dorsum of head pale with some dark markings. Pronotal lateral lobe with a characteristic dorsal yellow band that extends ventrally ............................................... N. rindu Robillard & Tan View in CoL sp. nov.

5. Frons with black band between eyes, mouthparts mostly yellow. Body darker; female FW typically with infumated black cells, with lateral parts of dorsal field usually with an infumated yellow longitudinal stripe. Distribution: Borneo (Sabah) ...................... N. danum Robillard & Tan View in CoL sp. nov.

– Frons without black band between eyes, mouthparts black. Body usually with more yellow colouration; male FW with some black and white infumation, but generally transparent. Distribution: Borneo, Malay Peninsula and Sumatra .......................................................................................................... 6

6. Legs usually pale in colouration; FIII with at least one black longitudinal stripe on external face. Male FW with distinct infumated white spots and infumated black pattern near base, sometimes with infumated white patterns around chords, but otherwise transparent, harp very small, with one distinct straight oblique vein; female FW almost always with yellow/white veins. Distribution: Sumatra .................................................................................................... N. insignis Saussure, 1878 View in CoL

– Legs usually brown in colouration; FIII with faint or without black longitudinal stripe on external face. Male FW with infumated black pattern near base, sometimes with infumated white spots, but otherwise transparent, harp larger, with 3 oblique veins; female FW sometimes with yellow/white veins. Distribution: Sumatra, Borneo, Malay Peninsula ................................................................... 7

7. Eyes dark when alive. Frons yellow, face part of fastigium (including scapes) and mouthparts black, maxillary palpi yellow; dorsal part of legs black. Male pseudepiphallus slender. Distribution: Borneo, near Kinabalu area .................................................................................... N. musicus Ingrisch, 1987 View in CoL

– Eyes green when alive. Frons yellow to brown, mouthparts sometimes yellow or brown; legs typically homogenous brown. Pseudepiphallus more robust, broad. Distribution: Sumatra, Borneo, Malay Peninsula ........................................................................................................................................... 8

8. Lighter in colouration. Lateral field of FWs usually light in colouration. Juveniles of pale white colouration with numerous dark stripes all around the body. Female copulatory papilla without truncated lobule at the ventro-anterior end. Distribution: Borneo, Sumatra ...................................... ...................................................................................................................... N. vittatus ( Haan, 1844) View in CoL

– Darker in colouration. Lateral field of FWs usually dark in colouration. Juveniles of darker colouration, usually grey, their pronotum without longitudinal stripes but dorsal disk sometimes with a large velvety black spot. Female copulatory papilla with a truncated lobule at the ventro-anterior end. Distribution: Malay Peninsula ................................................... N. malaya Robillard & Tan View in CoL sp. nov.