Diplopoda

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 : 9-11

Class Diplopoda ( Fig. 1 , 2)

“Throughout the temperate and tropical regions of the world, wherever local climatic conditions permit the accumulation of humus layers, the megascopic fauna of the forest floor is often dominated by species of the arthropod class Diplopoda.” So said R.L. Hoffman (1969a), and while millipeds also inhabit deserts, savannas, and prairies, geographic documentation of this statement is now, finally, available ( Fig. 1 ). Diplopoda is truly a global taxon that is indigenous, or presumed so, to all continents and continental islands, all of the East and West Indies, Iceland and Macaronesian islands in the Atlantic

Ocean, Madagascar and small islands in the In-

dian Ocean, both major islands of New Zealand,

and scattered, remote islands in the Pacific Ocean.

It is unknown from Arctic Ocean islands, Antarc-

tica, and subantarctic islands ( Hopkin and Read

1992, Minelli and Golovatch 2001, Golovatch and

Kime 2010); the most proximate locality to the

Antarctic Peninsula, of Penicillata / Polyxenida , lies

some 1,680 km (1,050 mi) to the north-northwest

in Santa Cruz Prov. , Argentina, while that of

Chilognatha, in Chubut Prov., Argentina, is some

2,960 km (1,850 mi) distant. Because of their

minute sizes, light, non-calcified bodies, and the

potential to be blown by winds and incidentally

transported by birds ( Tajovsky et al. 2001),

Polyxenida is the only order that plausibly may

someday be discovered on either the Antarctic Pen-

insula or subantarctic islands.

Diplopoda occupy enormous areas in both the

New and Old Worlds. There are two in the former,

an isolated point locality on Kodiak Island, Alaska,

USA, in the North Pacific Ocean, and a continu-

ous area extending from Yakutat, Alaska, USA, Figure 2. Distributions of Diplopoda, Chilognatha, and the “Haines Triangle,” Stewart, and Dawson Helminthomorpha, and Eugnatha in northwestern North Creek, BC, Ft. Severn, Hudson Bay, Ontario, America. The dot denotes Forrester Island, Alaska, USA. southern Labrador, and northern Newfoundland,

Canada, to southern Argentina and Chile. The latter encompasses all the continental US including the Channel Islands, off southern California, all of Mexico and Central America, all of the Bahamas and the Greater and Lesser Antilles, and all of South America except for southernmost Argentina / Chile and the Atacama Desert and adjoining arid areas in northern Chile and vicinity. We incorporate three Pacific Islands and archipelagos into this area – Cocos Island, Costa Rica; the Galapagos Islands, Ecuador; and the Juan Fernandez Islands, Chile – along with Fernando de Noronha, in the Atlantic off the eastern tip of Brazil, and we project Diplopoda for Turks and Caicos, Penicillata for Antigua and Barbuda, and Chilognatha for St. Kitts and Nevis. Several chilognath taxa potentially inhabit the first and last island nations, so we do not project orders.

In sub-Saharan Africa, Diplopoda exhibit a curvilinear northern border that extends from the Atlantic Ocean/ Senegal River, in the west, to the Red Sea at the Sudan / Eritrea border, in the east. We expand this area eastward to encircle southwestern Saudi Arabia / Yemen, Sokotra, the Comoros and Seychelles Islands, and Mauritius, Rodriguez, and Madagascar; on the west/Atlantic, we include Bioko (= Fernando Po), São Tomé and Principe, St. Helena, and the Cape Verde Islands, the last shared with “Euroaustralasia” because of potentially indigenous taxa with Afrotropical and Palaearctic/European affinities.

The enormous “Euroaustralasian” area begins in the Atlantic with Iceland, Madeira, the Azores, Canary, and Cape Verde islands, and encompasses all North/Baltic Sea and Mediterranean islands, all of the UK and Ireland, and all of continental Europe except northernmost Scandinavia and Russia. The irregularly curvilinear northern border extends across Siberia and Asian Russia, drops southward in the Far East to the Sea of Okhotsk, and crosses the heart of Kamchatka. With a detached site in central Saudi Arabia, the southern border extends through two parts of Mediterranean Africa, across the Middle East (central Israel and southern Jordan / Iraq) into Iran, curves northward into southern Afghanistan and northcentral Pakistan, and then turns abruptly southward through western India to encompass Sri Lanka, the Maldive /Andaman/ Nicobar islands, in the Indian Ocean, and all of Indonesia including islands offshore of Sumatra and Java. To the north, the eastern border curves around the Kurile and Bonin Islands, Pohnpei (= Ponape), Federated States of Micronesia, Samoa, Tonga, and Fiji, and we continue it southward to incorporate New Zealand, Tasmania, and southern and eastern Australia. Although the Deccan Plateau, India, western China / Mongolia, and parts of the Central Asian Republics lack records,

the Asian part of this area includes all of Tajikistan, Nepal, Bhutan, Bangladesh, Myanmar, Thailand, Japan (including the Ryukyu Islands), Taiwan, the Philippines, Singapore, Indonesia, Papua New Guinea, Vanuatu, New Caledonia, the Solomon Islands, and New Zealand plus the Indochina, Malay, and Korean peninsulas,

Diplopoda are known from three small Australian areas in addition to the eastern and southern coastlines, included with Eurasia. The largest is the westernmost coastal region of Western Australia, which spreads inland and along the northern and southern coasts, and there are two smaller “outlier” areas to the northeast, one in the Kimberley Region and another on the coast of Northern Territory that ranges 50 km (31.3 mi) inland.

Kodiak Island, Alaska (denoted by the left arrow in Fig. 1 ), the Hawaiian Islands, and the Federal Republic of the Marshall Islands (indicated by the right arrow) cannot be feasibly combined with one of the continents and are shown as separate.

The ranges of Diplopoda and Chilognatha ( Fig. 1 , 5 ) are nearly identical; Penicillata’s ( Fig. 3 ) impact on the former is minimal. It extends the class’ range southward beyond Chilognatha in both South America and North Africa, where it accounts for the bulk of the area by its occurrence in a Saharan oasis in southern Algeria. It is also responsible for the record from Federal Republic of the Marshall Islands and accounts for the coastal part of the Kimberley Region in Western Australia. With these few exceptions, the taxon Penicillata is entirely subsumed within the much larger area of Chilognatha.

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 3. Known (solid lines) and projected (dashed lines) indigenous distributions of the Subclass Penicillata and Order Polyxenida. The arrow denotes the record from the Federal Republic of the Marshall Islands; the upright question mark (?) denotes the unsubstantiated record of Propolyxenus patagonicus (Silvestri, 1903) from Santa Cruz Prov., Argentina (Mauriès 1998); and the inverted question mark (¿) indicates uncertain occurrence on the Yucatan Peninsula, Mexico. Other parameters as in Fig. 1. Too few records exist from Canada to project a northern boundary in North America, and the isolated record from central Asia (Kyrgyzstan) is too distant to be combined with an area where records cluster. No records are available from the dotted areas in India and North America, and the only one from that in Africa is Chilexenus schultzei (Attems, 1909) from Botswana (Hamer 1998).

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.