Pincer-like claws in centipedes (Chilopoda): multiple evolutionary origin of similar form and serial pattern

Abstract

In most Chilopoda, the walking legs end in a\ud single-tip claw usually accompanied by short accessory\ud spines. Instead, in all species of three small and only distantly\ud related geophilomorph taxa (Diphyonyx, Neogeophilidae,\ud Eucratonyx), the claws of an anterior set of leg\ud pairs are unusually pincer-like. By integrating different\ud microscopic techniques, including confocal laser scanning\ud microscopy, we found that these modified claws are very\ud similar in form, internal structure, and pattern of variation\ud in shape along the trunk in all three taxa: the claws are\ud distinctly swollen and bent, provided with peculiar bulges,\ud and flanked by a conspicuous additional branch, either\ud cylindrical or flattened, which overreaches the tip of the\ud claw; instead, the internal cuticular features are not modified\ud with respect to the condition in the other centipedes,\ud claiming against the possibility of controlled abduction/\ud adduction between claw and branch. Irrespective of the\ud total number of leg pairs (63–129), the claws change\ud gradually from pincer-like to usual shape invariantly in the\ud range spanning between the 34 and the 45% of the total\ud number of leg pairs. Despite these similarities, pincer-like\ud claws originated independently in the three taxa, and by\ud way of fundamentally different changes, either by the\ud dramatic modification of the already existent anterior\ud accessory spine (Diphyonyx, Neogeophilidae) or by the production of a novel cuticular projection (Eucratonyx).\ud Moreover, their shared pattern of variation along the body\ud was most probably constrained by already operating\ud developmental processes controlling the longitudinal patterning\ud of the trunk

A further contribution to the knowledge of Pectiniunguis minutus (Demange, 1968), a little known dwarf schendylid centipede from western equatorial Africa (Chilopoda: geophilomorpha)

“…All measurements are given in mm. Terminology for the external anatomy follows Bonato et al (2010Bonato et al ( , 2011. The following abbreviation was used in the text and legends of the figures: a.a., antennal article/articles.…”

A new soil centipede from South-East Asia with a unique arrangement of ventral glands, and a revised synopsis of Gonibregmatidae (Chilopoda, Geophilomorpha)

“…Bonato et al 2011: 23.Reported specimens – ≥7.Type locality – “New Britain” [Papua New Guinea].Geographical records – Indonesia: Ambon Island (Attems 1927); Dabra, in New Guinea (Chamberlin 1939); “Seltutti”, in Aru Islands (Ribaut 1912). Papua New Guinea: Madang (Attems 1914); New Britain (Pocock 1899); Ralum, in New Britain (Attems 1914); New Ireland (Bonato et al 2011). Eucratonyxmeinerti (Pocock, 1889) Original description – Pocock 1889: 289, fig.…”

“…38, as Eucratonyxmeinertii [sic]. Bonato et al 2011: 23, figs 5, 6d, 7i–l. Koch and Edgecombe 2012: 28, 48, figs 20–21.…”

“…Bonato et al 2014: figs 2b, 8b.Reported specimens – >12.Type locality – “Sullivan Island” [=Lanbi Kyun, Myanmar].Geographical records – Myanmar: Great Coco Island (Pocock 1891, as Himantariummeinertii [sic]); Lanbi Kyun, in Mergui Archipelago (Pocock 1889, as HimantariumMeinerti [sic]); Little Coco Island (Silvestri 1919, as Eucratonyxmeinertii [sic]); Mawlamyine (Pocock 1891); Palon (Pocock 1891); Reef Island, near Dawei (Pocock 1891). Thailand: Doi Inthanon (Bonato et al 2011). Disargusstriatus (Pocock, 1890) Original description – Pocock 1890: 248, fig.…”

“…The latter name was replaced with Sogophagus since Chamberlin (1912) because it was a junior homonym of a genus of Coleoptera. The species was suspected to belong to Eucratonyx by Bonato et al (2011). Tweediphilusmalaccanus Verhoeff, 1937 Original description – Verhoeff 1937: 225, figs 18-25.Other sources for morphology – Verhoeff 1941: 87. Wang and Tang 1965: 444.Reported specimens – ≥4.Type localities – “Gunong Brinchang” [=Gunung Brinchang, Indonesia] and “Telom Valley bei Gunong Siku” [=Telom Valley, near Gunung Siku, Indonesia].Geographical records – Malaysia: Gunung Brinchang, in Peninsular Malaysia (Verhoeff 1937); Telom Valley, near Gunung Siku, in Peninsular Malaysia (Verhoeff 1937).…”