Monseremus Ingrisch, 2018

Tan, Ming Kai, Japir, Razy, Chung, Arthur Y. C. & Robillard, Tony, 2022, A review of the genus Monseremus Ingrisch, 2018 (Orthoptera, Stenopelmatoidea Gryllacrididae) from Borneo, Zootaxa 5165 (1), pp. 107-114 : 108-109

Genus Monseremus Ingrisch, 2018

Monseremus Ingrisch, 2018: 222

Monseremus — Cadena-Castañeda 2019: 79

Type species. Monseremus appendiculatus Ingrisch , by monotypy and original designation

Included species.

Monseremus appendiculatus Ingrisch, 2018

Monseremus bellus (Tan & Wahab, 2018) comb. nov.

Distribution. Borneo (East Malaysia: Sabah; Brunei Darussalam: Temburong)

Remarks. The two species are very similar in general morphology, size and colouration in both males and females. Only the female subgenital plate and male tenth abdominal tergite show clear-cut species differences ( Fig. 2 ). The female tenth abdominal tergite and epiproct did not exhibit species differences ( Fig. 3 ).

The number of pegs on the two stridulatory files on each of the second and third tergites can be variable within species (second tergite ♂ ♀ 4–6, ♂ ♀ 12–14; third tergite ♂ 12–14 and ♀ 15–17, ♂ ♀ 16–19 in Monseremus bellus comb. nov. [n = 4♂, 4♀]) and do not appear show clear species differences (vs. ♂ ♀ 4–5, ♂ ♀ 11–13; ♂ ♀ 15–17, ♂ ♀ 16–18 in Monseremus appendiculatus [n = 2♂, 2♀]) ( Fig. 3 ). Likewise, the shape of the stridulatory files are also not different between the two species ( Fig. 3 ). Hence, these characters are unlikely to be important for species diagnosis.

Key to known species

1. Female: projections at the anterior margin of the subgenital plate larger, more bulbous (in lateral view), and longer in length than subgenital plate ( Figs 2A, 2B ). Ovipositor longer, length>17.0 mm. Male: medial processes of the tenth abdominal tergite with inner margins and apices clearly separated ( Fig. 2C ). Subgenital plate faintly more squarish, ca. 1.7 times wider than long ( Fig. 2C ). Distribution: highland forests in Sabah, East Malaysia.......................... Monseremus appendiculatus

-. Female: projections at the anterior margin of the subgenital plate smaller, more flattened (in lateral view), and shorter in length than subgenital plate ( Figs 2D, E ). Ovipositor shorter, length <16.5 mm. Male: medial processes of the tenth abdominal tergite with inner margins and apices touching each other ( Fig. 2F ). Subgenital plate more transverse, ca. 2.5 times wider than long ( Fig. 2F ). Distribution: lowland forests in Brunei Darussalam..................................... Monseremus bellus

Figures

FIGURE 2. Monseremus appendiculatus (A–C) and Monseremus bellus (D–F): female subgenital plate in ventral (A, D) and lateral (B, E) views; male abdominal apex in ventral view (C, F). Scale bars: 1 mm.

FIGURE 3. Monseremus appendiculatus (A, B) and Monseremus bellus (C, D): female abdominal apex in posterior view (A, C); female stridulatory files on second and third tergites (B, D). Scale bars: 1 mm.