Helminthomorpha, Pocock, 1887

Shelley, Rowland M. & Golovatch, Sergei I., 2011, Atlas of Myriapod Biogeography. I. Indigenous Ordinal and Supra-Ordinal Distributions in the Diplopoda: Perspectives on Taxon Origins and Ages, and a Hypothesis on the Origin and Early Evolution of the Class, Insecta Mundi 2011 (158), pp. 1-134 : 21

Infraclass Helminthomorpha (Fig. 2, 14)

The distribution of Helminthomorpha ( Fig. 14 ) is nearly identical to that of Chilognatha ( Fig. 5 ), to which readers are referred for details, as Pentazonia barely impact the latter’s range; the New World, Eurasian, sub-Saharan African, and oceanic occurrences are identical. The only difference, barely perceptible, is in coastal Western Australia, where Helminthomorpha do not extend quite as far eastward along the southern coast. Most helminthomorph occurrences are attributable to Eugnatha ( Fig. 24 ); Colobognatha ( Fig. 15 ) have minimal impact and are largely subsumed within the former’s area. Colobognatha extend Helminthomorpha westward in the Atlantic to encompass St. Helena and north of the Arctic Circle in Asian Russia; otherwise, helminthomorph distribution is attributable to Eugnatha alone.

Archidesmus macnioli Peach, 1887 , the earliest helminthomorph fossil ( Fig. 1 , 5 , 14 , upright triangle), from Silurian deposits in Scotland, came from either Avalonia itself or Laurentia after it collided with Baltica+Avalonia. It is not definitely assignable to either a modern or an extinct order.

Figures

Figure 1. Known (solid lines) and projected (dashed lines) indigenous distributions of the Diplopoda showing locations of significant fossils. The solid line in southern South America shows the extent of diplopod samplings and known occurrences, but we project the organisms for uninvestigated areas south of the southernmost records, in Isla Grande de Chiloé, Chile, and Santa Cruz Prov., Argentina, the unsubstantiated record of the polyxenid from the last (Mauriès 1998), Propolyxenus patagonicus (Silvestri, 1903), being indicated by the question mark. Except for records from Kodiak Island, Alaska (Chordeumatida) (left arrow), the Hawaiian Islands (Cambalidea), and the Federal Republic of the Marshall Islands (Polyxenida) (right arrow), oceanic islands and archipelagos harboring ostensibly indigenous forms are grouped with the continent with apparent faunal affinity; the Cape Verde Islands are combined with both Africa and Europe because of dual affinities, Spirostreptidea and Glomerida/ Julida, respectively. Only a few records and samples, especially of Chilognatha, are available from the dotted areas in Africa and North America; no extant records and samples are available from those in Eurasia and South America. The southeast Asian area encircled by triangles is the only place where all 16 orders occur indigenously. Upright triangle, site of Archidesmus macnioli Peach, 1887, the oldest helminthomorph fossil, from Silurian deposits in Scotland; Star, site of the non-spinose oniscomorph pentazonian Carboniferous fossil at Mazon Creek, Illinois, USA; Inverted triangle, approximate location of Gobiulus sabulosus Dzik, 1975, the Cretaceous spirobolidan fossil in Mongolia; Asterisk, location of Protosilvestria sculpta, the Oligocene cambalidean fossil from Quercy, France (Mauriès 1992).

Figure 14-15. Distributions. 14) Known (solid lines) and projected (dashed lines) distributions of the Infraclass Helminthomorpha showing the locations of significant fossils, parameters as in Fig. 1. It differs from that of the Subclass Chilognatha (Fig. 5) in the imperceptibly shorter length along the southern coast of Western Australia, the only place where Pentazonia have been taken without helminthomorphs. Upright triangle, site of Archidesmus macnioli Peach, 1887, the oldest fossil, from Silurian deposits in Scotland; Inverted triangle, approximate location of Gobiulus sabulosus Dzik, 1975, the Cretaceous spirobolidan fossil from Mongolia; Asterisk, location of Protosilvestria sculpta, the Oligocene cambalidean fossil in Quercy, France (Mauriès 1992). 15) Known (solid lines) and projected (dashed lines) distribution of the Subterclass Colobognatha. The question marks in Australia represent generalized records from Northern Territory, South Australia, and “Upper Western Australia” by Black (1997). Some point localities probably represent the ubiquitous, introduced polyzoniidan (Siphonotidae), Rhinotus purpureus (Pocock, 1894).

Figure 5-6. Distributions. 5)Known (solid lines) and projected (dashed lines) indigenous distributions of the Subclass Chilognatha showing the locations of significant fossils, parameters as in Fig. 1. It is essentially identical to that of the Infraclass Helminthomorpha (Fig. 14), the only difference being imperceptibly greater eastward expansion for Chilognatha on the southern coast of Western Australia. At present, this is the only place in the world where the Infraclass Pentazonia (Fig. 6) influences the overall distribution of a higher diplopod taxon. Upright triangle, site of Archidesmus macnioli Peach, 1887, the oldest helminthomorph fossil, from Silurian deposits in Scotland; Star, site of the non-spinose oniscomorph pentazonian Carboniferous fossil at Mazon Creek, Illinois, USA; Inverted triangle, approximate location of Gobiulus sabulosus Dzik, 1975, the Cretaceous spirobolidan fossil from Mongolia; Asterisk, location of Protosilvestria sculpta, the Oligocene cambalidean fossil in Quercy, France (Mauriès 1992). 6) Distribution of the Infraclass Pentazonia, which presently excludes the Yucatan Peninsula, Mexico. The question mark represents the unconfirmed Oniscomorpha (Sphaerotheriida) record from Papua New Guinea (Attems 1943), and the arrow denotes the new Limacomorpha/Glomeridesmida locality in Fiji (Appendix). Star, site of the non-spinose oniscomorph Carboniferous fossil at Mazon Creek, Illinois, USA.

Figure 23-25. Distributions. 23) Distribution of the “minor” orders. Star/Circled Areas, Siphonocryptida (Colobognatha); Dots, Siphoniulida (Helminthomorpha incertae sedis). 24) Known (solid lines) and projected (dashed lines) distributions of the Subterclass Eugnatha showing the locations of significant fossils. The arrow points to the Kodiak Island, Alaska, USA, record of Chordeumatida (Tingupidae). Inverted triangle, approximate location of Gobiulus sabulosus Dzik, 1975, the Cretaceous spirobolidan fossil from Mongolia; Asterisk, location of Protosilvestria sculpta, the Oligocene cambalidean fossil in Quercy, France (Mauriès 1992). 25) Known (solid lines) and projected (dashed lines) distributions of the Superorder Juliformia showing the locations of significant fossils. Parameters as in Fig. 1 except no records or samples are available from the dotted area in North America, the Great Basin Physiographic Province, western USA. Inverted triangle, approximate location of Gobiulus sabulosus Dzik, 1975, the Cretaceous spirobolidan fossil from Mongolia; Asterisk, location of Protosilvestria sculpta, the Oligocene cambalidean fossil in Quercy, France (Mauriès 1992). The question mark indicates the generalized record of Epinannolenidea from Northern Territory, Australia (Black 1997).