Nannaria Chamberlin, 1918

Means, Jackson C., Hennen, Derek A. & Marek, Paul E., 2021, A revision of the minor species group in the millipede genus Nannaria Chamberlin, 1918 (Diplopoda, Polydesmida, Xystodesmidae), ZooKeys 1030, pp. 1-180 : 1

Genus Nannaria Chamberlin, 1918

Type species.

Nannaria minor Chamberlin, 1918, by original designation.

Other taxa included.

61 species.

Diagnosis.

Members of the genus Nannaria are distinct from other genera of the subfamily Rhysodesminae , except the monotypic genus Oenomaea , by the twisted spatulate shape of the pregonopodal claws in males (Fig. 2 ) vs. bisinuately curved shape in other genera of Rhysodesminae . Nannaria vary from the contribal Oenomaea by the more rounded paranota in Nannaria (vs. more acute and hook-like in Oenomaea ) and the unique gonopodal characters of Oenomaea , as discussed in Hoffman (1964).

Short description.

Small-bodied (17.3-38.5 mm BL, 2.9-6.0 mm B11W) ‘flat-backed’ xystodesmid millipedes. Color: paranota red, orange, white, or (rarely) yellow-rarely connected by concolorus metatergal stripes. Background drab, ranging from pale tan to deep black. Male exoskeletal characters: sterna with paramedian lobes between 4th pair of legs; caudal margins of 8-18 sterna modified into subcoxal spines. Pregonopodal tarsal claws spatulate [(Fig. 2 )-note: the twisted spatulate shape of the pregonopodal claws in males is a unique autapomorphy and uniformly present in the tribe Nannariini ( Oenomaea pulchella and Nannaria species)]. Postgonopodal tarsal claws bisinuate. Male gonopodal characters: gonopods variable, often crossing, when viewed in situ; co-planar with coxae, lacking torsion, generally simple in comparison to other Rhysodesminae -though some species display elaborate curvature and ornamentation. Gonopods never bulky as in some Apheloriini . Prefemoral process present. Prostatic groove originating at cannula, terminating at acropodite tip. Acropodite, when viewed ventrally, c- or r-shaped. Gonopodal aperture lacking modified sternum. Gonocoxae connected by membrane and muscle.

Distribution.

Nannaria can be found in much of the eastern United States (Fig. 1 ): western Arkansas east to just outside Philadelphia (Pennslyvania), north to western New York, and south to central Mississippi. The southeastern edge of the distribution follows the Appalachian Mountains closely, though specimens from central North Carolina and Mississippi suggest that populations may eventually be found south of the Appalachians in states such as Texas and Florida. Likewise, scattered populations may exist in central and southern Illinois, as seen in neighboring Indiana and Missouri.

Etymology.

Derived from the Greek word nannos, for dwarf, referring to the comparatively small size of this genus within the Xystodesmidae .

Figures

Figure 1. The geographic distribution of Nannaria Chamberlin, 1918. Red: Nannaria minor species group; Purple: Nannaria wilsoni species group.

Figure 2. Scanning electron microscope image of a spatulate, twisted pregonopodal claw of a male Nannaria ericacea Hoffman, 1949.