Redescription of the Flatbacked Millipede 
Ilodesmus margaritifems (Gervais, 1836) (Diplopoda: 
Polydesmida: Platyrhacidae) from the Philippines 
Facundo M. Labarque Veverle D. A. San Juan 2-3^ 
Ireneo L. Lit, Jr. 2-3 and Charles E. Griswold i 
^ California Academy of Sciences, 55 Music Concourse Drive, San Francisco, CA 94118, USA; 
2 University of the Philippines Los Banos, College Los Banos, Laguna 4031, Philippines; 
2 Museum of Natural Histoiy, University of the Philippines Los Banos, College Los Banos, 
Laguna 4031, Philippines; ^ Biology Department, San Francisco State University, 
1600 Holloway Ave, San Francisco, CA 94132, USA;^ Environmental Science, Policy 
and Management, University of California, 101 Sproiil Hall, Berkeley’, CA 94704, USA;^ Biology 
Department, The George Washington University’, 2121 L St NW, Washington, DC 20052, USA. 
*Address coiTespondence to facundo. I aba rque@,gmai I. com 
Ilodesmus margaritifems (Gervais, 1836) is redescribed based on several male and 
female specimens from Mount Makiling, Laguna Province, Luzon Island, Philip¬ 
pines. Detailed illustrations of the head, antennae, gnathochilarium, mandibles, var¬ 
ious body rings, spiracles, legs, gonopods and eggs are provided. Platyrhacus philip- 
pinomm Chamberlin, 1921 and Polydesmus mey’enii Brandt, 1839 are here consid¬ 
ered junior synonyms of/, margaritifems. 
Keywords: alpha taxonomy; Indo-Malayan region; Platyrhacus philippinorum; Poly¬ 
desmus meyenii. 
Our knowledge on millipede morphology has inereased rapidly through the use of scanning 
electron microscopy in the last decade (Akkari and Enghoff 2011; Golovatch 2003; Golovatch et 
al. 2008, 2009a-b, 2011; Mesibov 2003, 2005, 2008, 2009a-K:, 2011, 2012; Rowe and Sierwald 
2006). Even though identifications of millipede species are merely based on the moiphology of the 
male copulatory organ, the gonopod, several recent works have documented morphological details 
in other structures such as: gonopores, fifth sternite lamella, spiracles, gnathochilarium and its 
palps, setae types, sensory cones (Rowe and Sierwald 2006), various tubercles processes, detail on 
the anal ring plates, spinnerets, limbus surface (Mesibov 2009a-b, 2012), sculpture of body rings 
and ozopores (Akkari and Enghoff 2011). The recent (2011) Filipino-American Hearst Biodiversi¬ 
ty Expedition to the Philippines enabled the collection of numerous millipedes and other terrestri¬ 
al arthropods, providing novel documentation of the remarkable species riclmess and endemism of 
Luzon. Among the specimens collected was new material of the flatbacked millipede Ilodesmus 
margaritiferus (Gervais, 1836), which enables us to redescribe the species and provide detailed 
illustrations of the head, antennae, gnathochilarium, mandibles, body rings, spiracles, legs, 
gonopods and eggs. These morphological features are described for the family Platyrhacidae for 
the first time. 
Systematics 
The family Platyrhacidae Pocock, 1895 is a large and diverse group of millipedes with 32 gen¬ 
era and more than 250 species, distributed in the Neotropical region between Pern and Nicaragua, 
in the Indo-Malaysian region in the Philippine archipelago and in the Australasian region in the 
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