Evolutionary trends and patterns in centipede segment number based on a cladistic analysis of Mecistocephalidae (Chilopoda: Geophilomorpha)

Abstract

Abstract. Evolutionary changes in segment number during the radiation of Mecistocephalidae, a group of geophilomorph centipedes with segment number usually invariant at the species level, were explored based on a cladistic analysis of forty‐six mecistocephalid species, representative of the extant diversity in segment number. The data matrix included 118 morphological characters. Trends were recognized in the evolution of segment number and discussed in relation to the underlying ontogenetic mechanisms of segmentation. The basic trend was towards an increasingly higher number of leg‐bearing segments, from (most probably) forty‐one to sixty‐five (101 in one exceptional case). Changes always involved even sets of segments. Additions of two, four or eight segments usually occurred, but a case of overall duplication of the whole number was also documented. Most changes occurred starting from values belonging to the arithmetical series forty‐one, forty‐five, forty‐nine, whereas the intermediate values forty‐three, forty‐seven, fifty‐one were often evolutionary dead‐ends. This evidence suggests a multiplicative mechanism of segmentation involving one or more final run of duplication, as well as a precise control of the final number of segments which produces absolute number stability, except for a single, highly derived species with an exceptionally high number of segments. These ideas contribute to a more general model of arthropod segmentation recently developed by Minelli. A taxonomic revision of mecistocephalids is presented: three subfamilies are proposed (Arrupinae, Dicellophilinae and Mecistocephalinae) and Sundarrup is recognized as a junior synonym of Anarrup.

Brooding in <I>Mecistocephalus togensis</I> (Geophilomorpha: Placodesmata) and the evolution of parental care in centipedes (Chilopoda)

“…Assuming the sister group relationship between Placodesmata and Adesmata (as had been defended by both morphological and molecular data before and independently of the discovery of Dicellophilus broods), and the monophyly of Mecistocephalidae (a result supported in published analyses; Bonato et al 2003), the new data from Mecistocephalus allow for the possibility that "dorsal surface inwards" could be convergent in Mecistocephalus and Adesmata, or that the general condition in Geophilomorpha is brooding with the dorsal surface inwards and Dicellophilus exhibits a reversal to the primitive state for Phylactometria as a whole. e data at hand do not permit a choice between these equally parsimonious optimisations.…”

A Moesian geophilomorph (Myriapoda: Chilopoda) species from the Carpathians: Review and redescription of Stenotaenia rhodopensis (Kaczmarek, 1970)

“…4); segments rather short, the terminal one has claviform sensory setae (sensilla basiconica) (according to the terminology of Foddai & Minelli 1999) in two groups (about 17 on the anterior side, and about 19 on the posterior surface) and three spearlike sensilla (sensilla brachyconica) on the tip (according to the terminology used by Bonato et al 2003).…”

The centipede genusMecistocephalusNewport 1843 in the Indian Peninsula (Chilopoda Geophilomorpha Mecistocephalidae)

“…A detailed description is provided for each species, entirely based on the specimens examined by us and describing all characters which are relevant within the entire Mecistocephalus genus. Morphological terms used here are explained in BONATO et al (2003). For each species, standard anatomical parts were drawn by means of a ''camera lucida'' from a representative specimen (an adult female whenever possible).…”

“…Pauroptyx Chamberlin 1920 is recognised here as a junior synonym of Mecistocephalus Newport 1843 (new synonymy). Pauroptyx was diagnosed on the basis of characters of the labrum and mandibles which also occur in other Mecistocephalus species probably not strictly related to each other (see BONATO et al 2003). Furthermore, to retain Pauroptyx as a segregate (sub)genus would require a corresponding treatment for dozens of often poorly circumscribed lineages within Mecistocephalus.…”

“…Mecistocephalus Newport 1843 is one of the most diverse and widespread genera of geophilomorph centipedes, with more than one hundred species recognised, mainly inhabiting the Oriental region (BONATO et al 2003). In spite of the faunistic relevance, the current taxonomy of the group is largely inadequate: many species still remain undescribed, the identity and distribution of most of those described are uncertain and the taxonomic validity of many nominal taxa needs to be reevaluated.…”