Pachymerium ferrugineum (C. L. Koch, 1835)

Figs 1 A, 2 A, 3

Geophilus ferrugineum C. L. Koch, 1835: 2.

Geophilus angustiventris Kessler, 1874: 44; Sseliwanoff, 1884: 78–80.

Geophilus caucasicus Attems, 1903: 256–257.

Geophilus felix Attems, 1947: 57, figs 24–26.

Geophilus kervillei Attems, 1908: 109; Attems 1929: 245.

Geophilus paradoxus Tömösváry, 1880: 619.

Arthronomalus puncticeps Lucas, 1849: 389.

Mecistocephalus punctilabium Newport, 1843: 179.

Pachymerium antipai Căpușe, 1968: 716; Popovici 2024: 590.

Pachymerium ferrugineum: Attems 1929: 245 –246, fig. 205; Takakuwa and Takashima 1949: 58; Wang 1956: 158; Bonato et al. 2004: 25, figs 4, 12, 14; Dyachkov 2018: 253, 2022: 71; Popovici 2024: 590, 594, figs 1 (A, B, D), 2; Bonato and Minelli 2014: 51.

Pachymerium ferrugineum helveticum Verhoeff, 1902: 559.

Pachymerium ferrugineum insulanum Verhoeff, 1902: 558.

Material examined.

670 specimens examined in this study are listed in Suppl. material 1.

Diagnosis.

Body length up to 60 mm; number of leg-bearing segments 39–63 (data on body length and number of leg-bearing segments compiled from Popovici 2024); clypeus with two clypeal areas and two poorly defined, pigmented areas close to posterior margin (Figs 2 A, 3 A). Labral mid-piece with 5–10 stout denticles; each side-piece entire, with ~ 15 bristles on lateral parts. Coxosternite of forcipular segment with anterior denticles; chitin lines incomplete, vanishing before reaching the condyle, ~ 0.6 × as long as the coxosternite. Coxopleuron with ~ 30 coxal pores in adults, opening independently on ventral and dorsal sides of coxopleuron.

Remarks.

This species exhibits a broad distribution across the west Palearctic, often introduced throughout the world (Bonato et al. 2011). Most recent publications concerning this species primarily update its distribution records, and describe cases of teratology (Bonato et al. 2004; Dyachkov 2018, 2022; Popovici 2024). Records show that this species transcends conventional habitat boundaries, with confirmed records from coastal regions through xeric shrublands to frigid alpine zones. In this study, female specimens of Pachymerium ferrugineum significantly outnumbered males across all samples. Given that all collected specimens were confirmed as conspecific (i. e., P. ferrugineum), the observed sex ratio bias is unlikely to result from species misidentification. Temporal analysis revealed that the number of male individuals collected in March and July exceeded that in other months, suggesting a possible link to the centipede’s reproductive cycle. Furthermore, male specimens were encountered more frequently in China’s Oriental region than in the Palearctic region. In addition, specimens from the Oriental region exhibited smaller maximum body length compared to those from the Palearctic region. Although sampling was conducted exclusively in vegetation-rich habitats, significant differences exist between the Oriental and Palearctic regions in terms of climate, humidity, and temperature fluctuations. Therefore, we hypothesize that the overall female-biased sex ratio and the observed morphological variations in this study may be associated with sampling months (and thus the reproductive cycle) as well as environmental conditions.

Distribution.

China (Gansu, Guangdong, Henan, Hubei, Hunan, Jiangxi, Jilin, Liaoning, Shaanxi, Shanghai, Shanxi, Sichuan, Taiwan and Yunnan provinces, Guangxi Zhuang Autonomous Region, Ningxia Hui Autonomous Region, Xinjiang Uygur Autonomous Region, Xizang Autonomous Region); all of Europe; Afghanistan; Algeria; Armenia; Azerbaijan; Cape Verde; Caucasus; Chile; Iraq; Japan; Kyrgyzstan; Mongolia; Morocco; North America; Tajikistan; Uzbekistan; Turkmenistan (Attems 1929; Takakuwa and Takashima 1949; Bonato et al. 2004; Dyachkov 2018, 2022; Popovici 2024).