Clidicostigus arachnipes Jaloszynski, Brunke & Bai 2017
Creators: name: Cao, Hai-Jing
name: Liu, Yu-Wei
name: Liu, Hao-Yu
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Staphylinidae
Clidicostigus
Clidicostigus arachnipes

description: Clidicostigus arachnipes Jałoszyński, Brunke & Bai, 2017
(Figs 1‒6, Table 1)
Clidicostigus arachnipes Jałoszyński, Brunke & Bai, 2017: 112, fig. 2A‒B; Jałoszyński, 2018: 109, fig. 163; Jałoszyński et al., 2018: 19, fig. 1E; Ross, 2024: 36.
Cascomastigus monstrabilis Yin & Cai, 2017: 2, fig. 1a‒d. Synonymized by Yin & Zhuo, 2019: 241.
Examined material. Thirteen specimens (MHBU, No. BU-COL-SCY001-013) in thirteen pieces of Myanmar ambers; deposited in MHBU.
Descriptive notes. Body length 5.40–7.50 mm (Table 1), black (Fig. 1; Yin et al., 2017) or dark brown (Fig. 2; Jałoszyński et al., 2017: fig. 2A). Head length 0.60–1.20 mm (Table 1). Labial palpus (Fig. 1C) moderately long, composed of elongate palpomere I, rod-shaped II, which is asymmetrical and broader than I, III narrowly subulate. Maxillary palpomere IV (Figs 1B, 2B, 3B, 4B, 5B) with enlarged apical part strongly bent basally. Antenna 4.19– 6.70 mm in length (Table 1), pedicel nearly 0.6–1.38 times as long as scape, antennomere IV about 1.3–2.2 times as long as III, V about 1.2–1.7 times as long as IV, VIII nearly as long as or feebly longer than IX (Figs 1A, 2B, 3B, 4B, 5B). Pronotum 1.2–1.84 mm in length, nearly twice as long as wide (Figs 1A, 2A, 3A). Each elytron (Figs 1A, 2A, 4A) with six striae. Protibia (Fig. 1B) with a subapical emargination.
Remarks. In the original description of this species (Jałoszyński et al. 2017), the elytron was described with four striae. Here the available specimen clearly shows that each elytron of this species has six striate (Figs 1A, 3A, 5A), as described by Yin et al. (2017).
Among our available materials, one specimen (MHBU, No. BU-COL-SCY006) seems different in the shape of pronotum, which is about 1.2 times as wide as long (Fig. 6A). However, it is of a poor quality because of a high degree of carbonization and deformation. But it can be treated as this species on the basis of the large body size (6.2 mm in length), elongate maxillary palpomere IV (Fig. 6B), and antennomere III evidently shorter than IV (Fig. 6A). In C. minor (Yin et al. 2018), the body is smaller (4.0 mm in length), maxillary palpomere IV rather stout, narrowed at base and rounded at apex, and antennomeres III and IV subequal in length.
Discussion. Although dozens of ambers are obtained in the present study, we have not found any additional species of the genus Clidicostigus at the moment. Instead, we consider that C. arachnipes is a highly variable species, exhibiting significant variations in body size, antennal length, and the relative lengths of antennomeres. As indicated in Table 1, body length, which may vary considerably due to different preservation states and observation angles, can serve as a useful criterion for species identification, given that C. arachnipes is consistently larger (longer than 5.4 mm) than C. minor (approximately 4.0 mm). Accordingly, individuals with larger body sizes tend to possess longer antennae and antennomeres.
Despite the variations observed in the available specimens of C. arachnipes, it should be kept in mind that at least a part of the variability can be attributed to a very poor preservation, distortion, and measurements carried out at various angles (an issue that reflects methodological error), as highlighted by Yin et al. (2020). Consequently, caution and meticulous comparisons are essential when establishing additional new taxa. Any further new species of Clidicostigus should be based solely on the stable and unique combination of male features, such as body size and the shape of maxillary palpomeres, among others.
description: Published as part of Cao, Hai-Jing, Liu, Yu-Wei & Liu, Hao-Yu, 2025, Taxonomic notes on † Clidicostigus arachnipes Jałoszyński, Brunke & Bai, 2017, a predominant ant-like stone beetle in the mid-Cretaceous Burmese amber, pp. 493-500 in Zootaxa 5621 (4) on pages 495-499, DOI: 10.11646/zootaxa.5621.4.8, http://zenodo.org/record/15263131