Nicklephyllum acanthonotum (Nickle, 1985)

Heller, Klaus-Gerhard & Helb, Matthias, 2024, Description of the female of Nicklephyllum acanthonotum (Nickle, 1985) and remarks on Steirodontini problems (Orthoptera: Tettigonioidea, Phaneropterinae), Zootaxa 5543 (4), pp. 597-599 : 597

In 1985, the species Nicklephyllum acanthonotum was described by Nickle as a member of the genus Stilpnochlora .

The type material consisted from three intact males and one female without abdomen. Feeling that „in its general appearance, acanthonotum is not easily recognized as belonging to the genus“ Stilpnochlora, Nickle was unhappy about the missing female and wrote „When a complete female of this species is found, these characters should clarify the generic affinities of acanthonotum “. More than 30 years later, Cadena-Castañeda (2016) studied the American tribe Steirodontini (‚giant katydids‘) Stilpnochlora is assumed to belong to and created a new monotypic genus for Nickle’s species—still without knowing the female. First figured by Linsenmaier (1972) and unmistakeable from its pronotal shape, the species is obviously relatively widespread from Panama in the North to Ecuador in the South (iNaturalist 2024).

By serendipity we obtained a female of the species, collected 2019 in Ecuador, allowing the study of the characteristics Nickle was looking for. The animal was collected in ECUADOR: Pichincha, Mashpi , [ 0.16N, - 78.90E], 600 m a.s.l., 28 v 2019 (label see Fig. l C). Its measurements [length (head to apex of tegmen) 92 (mean 79; from Nickle 1985) mm; length pronotal disc 13 (11) mm; posterior width pronotal disc 8.5 (8) mm; length posterior femur 39 (34) mm; width posterior femur 3.5 (3) mm; length tegmen 84 (69) mm; width tegmen 20.5 (16) mm] surpass the male data slightly. According to Nickle (1985), the females of the three other genera of Steirodontini sensu Emsley (1970) [and Cadena-Castañeda (2016)] are characterized by the presence ( Steirodon , Cnemidophyllum ) or absence ( Stilpnochlora ) of processes on the 8th and 9th tergite (females of the monotypic genera Emsleyfolium Cadena-Castañeda et al., 2016 and Coronophyllum Mendes et al. 2023 unknown). The female of Nicklephyllum acanthonotum does not have such processes ( Fig. 1 ; compare Emsley, 1970, p. 215: fig. 51 versus fig. 47-50, 52-54), thus supporting Nickle’s original grouping. The ovipositor is „strongly upturned at base and apically pointed“ as also shown for Stilpnochlora in Emsley’s fig. 51 ( Emsley 1970). Directly above the base of the ovipositor a pair of small sclerites is found ( Fig. 1 B ), not mentioned for any other genus or species of the group. The pattern of the crossveins which carry the female stridulatory files is similar in Nicklephyllum and Stilpnochlora couloniana ( Fig. 2 ; female obtained by commercial breeder), but is unstudied in all other genera.

Accepting generic status for the spiny Nicklephyllum acanthonotum , the species may nevertheless be closer to Stilpnochlora which has mostly only few weak tubercles on the pronotal carinae if any than to the other genera of Steirodontini sensu Emsley (1970) which carry typically distinct tubercles or spines. This phylogenetic hypothesis may have taxonomic implications since the definition of Steirodontini is not undisputed. Brunner von Wattenwyl (1878) included Trigonocorypha , Steirodon (with subgenera), Stilpnochlora and Xantia into this group (his „Steirodontia“), while Emsley (1970) excluded Trigonocorypha and Xantia . Molecular data, however, suggest that Asian Trigonocorypha and American Steirodon and Cnemidophyllum form a monophyletic branch, which is surprising from biogeography. Stilpnochlora —and perhaps Nicklephyllum —seems to belong somewhere else, near to Microcentrini ( Mugleston et al., 2018). Madagascan Trigonocorypha are found among African genera, next to Terpnistria . Brunner von Wattenwyl’s (1878) grouping of very large species with crenulate pronotal carinae may thus be one of the many examples of „extensive ecomorph convergence and …taxonomic incongruence“ among Tettigonioidea ( Mugleston et al., 2018).

Figures

FIGURE 1. Ovipositor and terminal segments of female Nicklephyllum acanthonotum. A Left lateral view; B Dorso-posterior view; C Label. Scale A, B 5 mm.

FIGURE 2. Pattern of the crossveins carrying the stridulatory files in right tegmen of Nicklephyllum acanthonotum (A) and Stilpnochlora couloniana (B). Scale 5 mm.