PYRGODESMIDAE, Silvestri, 1896

Shelley, R. M., 2004, The milliped family Pyrgodesmidae in the continental USA, with the first record of Poratia digitata (Porat) from the Bahamas (Diplopoda: Polydesmida), Journal of Natural History 38, pp. 1159-1181 : 1161-1164

Family PYRGODESMIDAE

Pyrgodesmidae Silvestri, 1896: 192 ; Hoffman, 1999: 473–474; Shelley, 2001: 246. Stylodesmidae Cook, 1895: 5 ; Chamberlin, 1943: 62; Chamberlin and Hoffman, 1958: 76. Stiodesmidae Cook, 1896: 25 ; Loomis, 1944: 175.

Diagnosis (adapted from Hoffman, 1982; Golovatch, 1996, 2001). Small-bodied Polydesmidea incapable of enrolling into a spiral, usually colourless or black, 3–15 mm in length with 19 or 20 segments, including epiproct, as adults; antennae with article 5 longest; collum enlarged and flabellate, usually partly or completely covering head in dorsal view, anterior margin indented to varying degrees forming scallops or lobes; paranota large, margins incised or lobed, at least some ozopores located on elongated, tubular ‘porosteles’; metaterga typically roughened and without, or with only inconspicuous, setation, surface pustulate or tuberculate to varying degrees, paramedian tubercles often enlarged into subparallel longitudinal crests.

Distribution in the USA. Northern, central and southern Texas; western and northern Louisiana through north-central Alabama to coastal Georgia and southward throughout peninsular Florida and the Keys; greenhouses in Illinois (figures 1, 2); also occurring in Hawaii, Puerto Rico and the US Virgin Islands. Golovatch (1996) mapped the family’s distribution worldwide with Florida, the Gulf Coastal fringe and extreme southern Texas shaded. This area is generally accurate, but it extends farther northward in Alabama, Louisiana and Texas, and pyrgodesmids have not been encountered in southeastern Texas. I regard the absence of records from the western Florida panhandle as an artifact reflecting lack of collecting and shade the entire state in figure 1.

Remarks. Hoffman (1976) noted the synonymy of Stylodesmidae with Pyrgodesmidae and that the latter holds priority.

The widespread occurrence of parthenogenesis in the Pyrgodesmidae has been noted by Shelley and Golovatch (2001), Golovatch and Sierwald (2001) and Golovatch et al. (2001), and it should be reiterated that this is true of US populations of Poratia digitata , P. obliterata and Calyptodesmus sanctus . No males have ever been collected here of these species.

It is possible to confuse the ornamented, pustulate, small-bodied polydesmidan, Prosopodesmus jacobsoni Silvestri (Haplodesmidae) , introduced into Florida and Louisiana (Shelley and Golovatch, 2000), with representatives of the Pyrgodesmidae . The following key distinguishes these taxa and representatives of the Pyrgodesmidae in the continental USA.

Key to the Pyrgodesmidae in the Continental USA

1 Paranota at most only slightly declined, extending generally horizontally, subparallel

to substratum; ozopores positioned at paranotal margins; Georgia and Florida to Texas and the Rio Grande, Illinois (native and introduced)... Pyrgodesmidae : 2

– Paranota strongly declined, extending nearly perpendicularly, directed ventrad (downward) toward substratum; ozopores removed from paranotal margins; Florida, Louisiana (introduced)..... Haplodesmidae : Prosopodesmus jacobsoni Silvestri

2 Scallops on collum completely and widely separated from each other, except for two

lateral-most, which are fused basally and slightly indented (figure 3)......

................. Poratia Cook and Cook : 3 – Scallops on collum fused basally to varying degrees (figures 4–8)...... 4

3 Adults with 19 segments, largely with three lobes on paranota of segments 16–18;

Florida, Louisiana, Texas, Illinois ........ Poratia digitata (Porat)

– Adults with 20 segments, largely with four lobes on paranota of segments 16–18; Georgia.............. Poratia obliterata (Kraus)

4 Porosteles present on segment 9 (potentially present on segments 5, 7, 9, 10, 12, 13,

15 and possibly 16).................. 5

– Porosteles absent from segment 9 (potentially present on segments 5, 7, 10, 13, 15 and

possibly 16)............. Myrmecodesmus Silvestri : 7

5 Segment 16 with porosteles; poriferous paranota with one broad, subtruncated lobe

anterior to porosteles (figure 12); Florida .. ‘ Lophodesmus ’ bituberculatus Loomis

– Segment 16 without porosteles; poriferous paranota either with one narrowly rounded lobe anterior to porosteles or two lobes (figures 9–11)......... 6

6 Porosteles located at caudolateral corners of paranota; porostele bearing segments

mostly with two lobes anterior to porostele, segment 5 with only one (figure 10); Florida ................ Psochodesmus crescentis Cook

– Porosteles located between lobes near mid-lengths of paranota; porostele bearing segments with one lobe anterior to porostele, segment 5 also with one (figure 9); Florida, Georgia, Alabama ........ Calyptodesmus sanctus Schubart

7 Paramedian tubercles coalesced into moderate-size crests, diminishing in height on

segments 19–20, extending only slightly beyond level of epiproct, latter visible in dorsal view between carinae (figures 17, 18); Texas .. Myrmecodesmus reddelli , new species

– Paramedian tubercles coalesced into strong crests, greatly elevated above tergal surfaces on all segments, clearly extending beyond level of epiproct (figures 13–16)... 8

8 Caudalmost tubercles on segment 19 narrowly separated, obscuring epiproct in dorsal

view (figure 13); Louisiana, Texas .... Myrmecodesmus formicarius Silvestri

– Caudalmost tubercles on segment 19 widely separated, epiproct visible between them in dorsal view (figure 15); Florida to Louisiana .. Myrmecodesmus digitatus (Loomis)