Dicellophilus pulcher, (KISHIDA, 1928)

Bonato, Lucio, Dányi, László & Minelli, Alessandro, 2010, Morphology and phylogeny of Dicellophilus, a centipede genus with a highly disjunct distribution (Chilopoda: Mecistocephalidae), Zoological Journal of the Linnean Society 158 (3), pp. 501-532 : 524-527

DICELLOPHILUS PULCHER ( KISHIDA, 1928)

Mecistocephalus pulcher Kishida, 1928 . Original description: Kishida, 1928: 300. Type locality: Ichigome, Subashiri, Mt. Fuji (translated from Japanese) ( Japan). Type material: number of specimens unknown, at least one adult female; repository unknown; probably lost.

= Dicellophilus latifrons Takakuwa, 1934 . Original description: Takakuwa, 1934c: 355. Type locality: ‘Kaybara (Hyogo), Masudo (bei Tokyo), Komono (Miye), Ikao (Gumma), Ōta (Gumma), Odawara (Kanagawa), Suwa (Nagano)’ [= Kaibara; Masudo, near Tokyo; Komono; Ikao; Ota, in Gumma-ken; Odawara, in Kanagawa-ken; Suwa, in Nagano-ken ( Japan)]. Type material: number of specimens unknown, including a female; apparently originally retained in the personal collection of Y. Takakuwa, Tokyo; probably lost. Synonymy by Shinohara, 1983: 6.

= Dicellophilus japonicus Verhoeff, 1934 . Original description: Verhoeff, 1934: 32. Type locality: ‘Umgebung von Tokyo’ [= near Tokyo ( Japan)]. Type material: holotype female, 51-mm long, originally deposited in the Zoologische Staatssammlung München (code number ZSMA 20030254). Synonymy by Shinohara, 1983: 6.

= Tygarrup monoporus Shinohara, 1961 . Original description: Shinohara, 1961: 212. Type locality: ‘Manazuru’ [= Manazuru ( Japan)]. Type material: holotype female, 17-mm long, probably in the private collection of K. Shinohara. Synonymy by Uliana et al., 2007: 28.

Main references for morphology: Kishida, 1928: 300 (original description); Takakuwa, 1934c: 355 (redescription as D. latifrons ); Takakuwa, 1934b: 878 (diagnosis as D. latifrons ); Kishida, 1947: 935 (diagnosis); Verhoeff, 1934: 32 (redescription as D. japonicus ); Takakuwa et al., 1940: 82 (key and redescription as D. latifrons ); Shinohara, 1961: 212 (redescription as T. monoporus ); Uliana et al., 2007: 27 (redescription).

Diagnosis: A Dicellophilus species with 41 leg-bearing segments. Antennae about three times as long as the maximum width of the head, strongly tapering (width of the terminal article less than half of the width of article I); terminal article more than two times as long as wide, and less than 1.5 times as long as article XIII. The longest setae on the antennae are shorter than 200 Mm ( Fig. 5E ). Sensilla on the antennal tip ( Fig. 8D ) usually with a crown-like projection at about mid-length. Head ( Fig. 5A ) ~1.2–1.4 times as long as wide. Lateral margins of the cephalic plate markedly convex, evidently converging only in the posterior part. Frontal line ( Fig. 5C ) uniformly rounded. Clypeus ( Figs 5D , 8E ): lateral margins converging backwards; a wide subtriangular posteromedial area without setae, also without a distinctly isolated posteromedian pair of setae. Non-areolate part of the buccae ( Fig. 5D ) extending forwards, distinctly beyond the labrum. Mandible with between five and seven pectinate lamellae. Coxosternum of maxillae I ( Figs 5B , 9D ) less than three times as wide as medially long. Medial projection of maxillae I about two times as long as wide; distal hyaline part enlarged, subtriangular; hyaline scales present on the dorsal surface ( Fig. 5H ). Distal hyaline part of the telopodite of maxillae I distinctly longer than the basal chitinous part. Distal article of the telopodite of maxillae II subconical, tapering gradually along most of its length, ~1.5 times as long as wide ( Fig. 5B ). Condylar processes ( Fig. 5I ) of the forcipular coxosternum well developed. Forcipular article I about as long as wide, the tubercle relatively small, not or only slightly projecting beyond the distal margin of the article ( Figs 5F , 9E ). Forcipular tarsungulum with evident basal tubercle ( Fig. 9L ), the dorso-internal margin evidently crenulated, with variably spaced notches ( Fig. 9J, K ). Sternum of the last leg-bearing segment ( Figs 5G , 9F ) longer than wide. Posterior end of coxopleura indistinctly pointed.

The main differential characters in respect to the other Dicellophilus species are presented in Table 3.

Notes on taxonomy: The name M. pulcher was introduced by Kishida (1928) for a species previously indicated by the same author as Mecistocephalus sp. ( Kishida, 1927) . The name remained almost completely overlooked by subsequent authors, even though Takakuwa et al. (1940) commented on its possible identity with D. latifrons Takakuwa, 1934 , and Shinohara (1983) confirmed this view, however, without adopting the older name as valid. Dicellophilus pulcher was resurrected definitively as the valid name for the species by Uliana et al. (2007) within a comprehensive revision of Japanese mecistocephalids. Even though the type material of M. pulcher is probably lost (K. Ishii, H. Ono, K. Shinohara & N. Tsurusaki, pers. comm.), the identity of the species can be confidently recognized based on the original accounts and illustrations provided by Kishida (1927, 1928). It is worth noting that in introducing the name M. pulcher, Kishida (1928: 300) cited it as ‘ Mecistocephalus pulcher Kishida, 1925 ’, probably referring to the year when the species was collected, and not to a previous publication, as the name was not used in Kishida (1927).

Dicellophilus latifrons Takakuwa, 1934 was described by Takakuwa (1934b, c) from a series of specimens from different localities. Other specimens were later identified, and it has been used as the valid name for the species in all major publications dealing with Japanese geophilomorphs (e.g. Takakuwa et al., 1940; Attems, 1947; Murakami, 1993; Shinohara, 1999; Bonato et al., 2003), until Uliana et al. (2007) recognized it as a junior synonym of D. pulcher , and adopted D. pulcher as the valid name of the species. Based on the original papers by Takakuwa (1934b, c), it seems that the type material was retained in the personal collection of Y. Takakuwa, but at present the collection is impossible to locate, and is believed to have been lost during World War II (K. Ishii, H. Ono, K. Shinohara & N. Tsurusaki, pers. comm.).

Dicellophilus japonicus Verhoeff, 1934 was described by Verhoeff (1934) from a single specimen, but it was only used rarely in the literature ( Verhoeff, 1937; Attems, 1947; Kishida, 1947) because it was recognized as obviously being identical to D. latifrons , and indeed it has been recognized as a junior synonym of D. latifrons since 1938 ( Takakuwa et al. 1938b, 1940).

Tygarrup monoporus Shinohara (1961) was described by Shinohara (1961) from a single specimen. Even though no other specimens were identified, it was maintained as a valid species of Tygarrup by subsequent authors ( Titova, 1983; Murakami, 1993) until Uliana et al. (2007), based on the original description and illustrations provided by Shinohara (1961), recognized that the holotype was actually a juvenile D. pulcher . The type material was apparently retained in the private collection of K. Shinohara, Chiba (H. Ono, pers. comm.).

Notes on morphology: Previous published accounts of the species were found to be inaccurate in some morphological characters: invariantly separate labral side pieces were suggested by Verhoeff (1934) as distinguishing D. latifrons from D. carniolensis , where they often touch each other, but we found that the distance between the labral side pieces is variable in both species; small setae were described as being present on the buccae of D. latifrons by Takakuwa (1934c), but actually the buccae are invariantly devoid of setae in this, as in all other species, of Dicellophilus ; the basal article of the telopodite of the maxillae II was described as peculiarly shaped in D. japonicus by Verhoeff (1934), but we found that it is similarly shaped in all species of Dicellophilus ; the basal tubercle of the tarsungulum was sometimes described as being inconspicuous ( Verhoeff, 1934; Takakuwa et al., 1940; Shinohara, 1961), but it is actually more evident than in D. carniolensis ; the number of leg-bearing segments was given as 43 for D. japonicus by Attems (1947), followed by Mikoš (1991), but this is evidently erroneous, as revealed by the original description of the species ( Takakuwa, 1934c); coxal macropores were described as being relatively larger in adult D. latifrons than in adult D. carniolensis , by Verhoeff (1934), but their conspicuousness is actually similar in all species.

Distribution: The species occurs along most of the island of Honshu, from the Chugoku Mountains in the west to the Ou Mountains in the north ( Fig. 10 ). It has been recorded from around three dozen localities (reviewed by Uliana et al., 2007).

Notes on distribution: Titova (1983) suggested that T. monoporus (currently a junior synonym of D. pulcher ; see above) could also occur in eastern China, but no evidence to support this claim was presented.

PHYLOGENY

The analysis of the data set ( Table 1), including all four out-group taxa, and weighting characters equally, yielded a single most-parsimonious tree (42 steps; consistency index, CI = 0.71; retention index, RI = 0.79; Fig. 11 ). After successive weighting, a single most-parsimonious tree with identical topology was found (24.3 steps; CI = 0.89; RI = 0.93). Analyses performed including the single out-group species separately were based on 11–14 parsimonyinformative characters, depending on the out-group species. In all cases a single most-parsimonious tree was obtained, both weighting characters equally (depending on the out-group species, 19–32 steps; excluding uninformative characters, CI = 0.80–1.00; RI = 0.75–1.00) and after successive weighting (19–26 steps; excluding uninformative characters, CI = 1.00; RI = 1.00). The topology for the in-group was found to correspond with that obtained from the analysis including all four out-group taxa ( Fig. 11 ). In all analyses, high bootstrap values were obtained for all nodes: the Bremer index values, estimated from 2946 trees, 42–142-steps long, range from 2 to 7 ( Fig. 11 ).

The monophyly of the genus Dicellophilus is confirmed and supported by three unambiguous, nonhomoplastic synapomorphies: margin of the labral side pieces uniformly concave (character 11: 1) and bearing hair-like projections (character 13: 1), and each coxopleuron with one distinct macropore (character 29: 1). It is also supported by two other characters: mandibles covered with hair-like projections (character 14: 1), but this is homoplastic with respect to the out-group Proterotaiwanella ; and foraminal processes and associated grooves reaching the posterolateral corners of the coxosternum of maxillae II (character 19: 0), but this is a reversal.

The relationships among the species of Dicellophilus are resolved confidently, with D. carniolensis emerging as the most basal lineage, and D. pulcher closely related to the sister species D. anomalus and D. limatus ( Fig. 11 ).

The monophyly of the clade D. anomalus + D. limatus + D. pulcher is supported by two unambiguous, non-homoplastic synapomorphies: terminal antennal article elongate (character 1: 1); and medial projections of maxillae I bearing subtriangular distal parts (character 15: 1). It is also supported by four other character changes: medial projections of maxillae I bearing hyaline scales (character 16: 0), but this a reversal; distal parts of the telopodites of maxillae I elongate (character 17: 1); terminal articles of the telopodites of maxillae II subconical (character 21: 1); however, both the latter characters are homoplastic with respect to the out-group Anarrup ; and forcipular condylar processes distinctly elongate (character 25: 1), but this is homoplastic with respect to the outgroup Proterotaiwanella .

The monophyly of the clade D. anomalus + D. limatus is supported by four unambiguous, nonhomoplastic synapomorphies: antennal setae very elongate (character 2: 1); frontal line forming an evident angle pointing forwards (character 4: 1); clypeus bearing a distinctly isolated posteromedian pair of setae (character 8: 1); and coxosternum of maxillae II elongate along the lateral margins (character 18: 1). It is also supported by three other characters, although they appear to be reversals: relatively elongate cephalic plate with lateral margins evidently converging on most of their length (character 3: 0); tubercle of the forcipular trochanteropraefemur relatively large (character 26: 0); and sternum of the last leg-bearing segment wider than long (character 28: 0).

All character changes listed above have been reconstructed under both the AccTran and DelTran options.

Figures

Figure 5. Dicellophilus pulcher. A, head, dorsal view. B, right part of the maxillary complex, ventral view (detached from head). C, anterior part of head, dorsal view. D, clypeus and labrum, ventral view (maxillae removed). E, left antennal articles III–V, dorsal view. F, internal margin of left forcipule, dorsal view. G, last leg-bearing segment of an adult female, ventral view. H, left telopodite and medial projection of maxillae I, dorsal view (detached from head). I, left condylar process of forcipular coxosternum, dorsal view (head removed). Microscopic photographs and line drawings: ♀, 70-mm long, from Iwagasaki, Japan; the detailed data for the specimen are presented in the Material and methods.

Figure 8. Dicellophilus carniolensis (A–C) and Dicellophilus pulcher (D–F). A, D, apical sensillum on antennal article XIV. B, E, clypeus and labrum, ventral view (maxillae removed). C, F, medial part of labrum, ventral view (maxillae removed). Arrowheads: a, antennal apical sensillum; b, lateral margin of clypeus; c, anterior ala; d, thickened line between anterior and posterior ala; e, posterior ala; f, fold on posterior ala; g, mid-piece of labrum; h, marginal hair-like projections. SEM micrographs: A, D. carniolensis, ♀, 51-mm long, from Mara, Romania; B–C, D. carniolensis, ♀, 55-mm long, from Volovec, Ukraine; D–F, D. pulcher, ♀, 38-mm long, from Shiobara, Japan; the detailed data for the specimens are presented in the Material and methods.

Figure 9. Dicellophilus carniolensis (A–C, G–I) and Dicellophilus pulcher (D–F, J–L). A, D, maxillary complex, ventral view (detached from head). B, E, forcipules and anterior part of coxosternum, dorsal view (head removed). C, F, last leg-bearing segment and terminal segments, female, ventral view. G, J, forcipular tarsungulum, dorsal view. H, K, margin of forcipular tarsungulum, dorsal view. I, L, basal part of forcipular tarsungulum with basal tubercle, dorsal view. Arrowheads: a, telopodite of maxillae II; b, telopodite of maxillae I; c, medial projection of maxillae I; d, metameric pore of maxillae II; e, foraminal process of maxillae II; f, condylar process of forcipular coxosternum; g, cerrus; h, sternum of last leg-bearing segment; i, macropore; j, basal tubercle on forcipular tarsungulum. SEM micrographs: A, D. carniolensis, ♀, 48-mm long, from Valdobbiadene, Italy; B, D. carniolensis, ♀, 55-mm long, from Volovec, Ukraine; C, D. carniolensis, ♀, 51-mm long, from Mara, Romania; D–F, J–L, D. pulcher, ♀, 38-mm long, from Shiobara, Japan; G–I, D. carniolensis, ♀, 55-mm long, from Sighetu Marmaţiei, Romania; the detailed data for the specimens are presented in the Material and methods.

Figure 10. Geographical distribution and phylogenetic relationships of the species of Dicellophilus. The shaded areas indicate the established populations; stars indicate either occasional or dubious records. The dotted line indicates the 40 °N parallel of latitude.

Figure 11. Phylogeny of Dicellophilus: most-parsimonious tree obtained by the cladistic analysis of the complete data set (Table 1). At each node, the bootstrap values are indicated above, and the Bremer index values are indicated below and underscored; at each node of the in-group, the range of variation of the bootstrap values obtained in the alternative analyses, including a single out-group species each time, is indicated in square brackets. The character changes reconstructed under DelTran optimization are mapped onto the clades by means of rectangles: the code number of the character is indicated above, and the acquired state is indicated below; the changes reconstructed under both DelTran and AccTran optimization are in bold; full rectangles indicate non-homoplastic changes, empty rectangles indicate homoplastic changes.