Packardesmus cavicola ( Packard, 1877 )

Shear, William A. & Shelley, Rowland M., 2019, Solved after 140 years: the identity of the millipede Polydesmus cavicola Packard, 1877, and proposal of Packardesmus n. gen. (Diplopoda: Polydesmida: Macrosternodesmidae), Zootaxa 4559 (2), pp. 384-390 : 386-387

Packardesmus cavicola ( Packard, 1877)

Figs 1–7 .

Polydesmus cavicola Packard, 1877:161 .

Brachydesmus cavicola — Chamberlin & Hoffman, 1958:64.

Material examined: Type specimen. Female lectotype (MCZ) from Clinton’s Cave, Oquirrh Mountains , near Lake Point Station , Tooele County, Utah, collected by A. S. Packard, summer 1875. Non-type material. A male (described below) and three females were collected by W. R. Bosworth at the type locality on 15 June 2003. The male specimen, on which the description below is based, was dissected and mounted on an SEM stub, and will be deposited along with the females in the collection of the Virginia Museum of Natural History ( VMNH) .

Diagnosis. As is for the genus, see above.

Description. Based on male from Clinton’s Cave. Measurements: Length, 6.0 mm, greatest width, 0.6 mm. Eighteen rings (collum + 15 podous rings + one apodous ring + telson). Head densely and finely setose ( Figs 1, 2 ). Antennae ( Fig 1 ) relatively long, extending backward to posterior margin of third ring. Antennomeres 2–4 cylindrical, fifth slightly inflated, sixth much enlarged (5 and 6 both with apical accessory sensory areas), seventh pyriform, concealing eighth antennomere bearing usual four apical sensory cones. Base (cardo) of mandibles greatly exceeding width of collum when viewed dorsally ( Fig 2 ). Collum ( Fig. 2 ) arcuate anteriorly, with nearly straight posterior margin, bearing three rows of seven–eight setae; anterior and posterior rows at anterior and posterior margins of collum. Collum with small posterolateral tooth on each side. Setae of first row on collum long, acute, then becoming shorter, blunter by posterior row. Midbody rings ( Fig. 3 ) with paranota bearing four marginal teeth and acute posterolateral corner. Ozopores opening dorsally from distinct calluses ( Fig. 3 ). Metazonital setal rows on distinct tubercles, becoming more irregular posteriorly with outermost seta on each side moving to paranotal teeth on more posterior rings. Some setae of rows missing or additional setae present. First row becoming distinctly recurved on rings posterior to collum. Metazonital setae short, clavate, blunt ( Fig. 1 ). Pygidium with scattered setae. Gonopods ( Figs 4–7 ) set in rimmed, oval aperture. Gonocoxae subhemispherical, flattened mesally, immovable. Prefemur setose, transverse. Telopodite arising at right angle to prefemur, consisting of long stem topped by four acute, curved processes including acropodite and solenomere (s, Fig. 6 ) bearing seminal pore (p, Fig. 6 ).

Female from Clinton’s Cave (collected in 2003). Length, 6.0 mm, greatest width 0.66 mm. Nineteen rings (collum + 16 podous rings + one apodous ring + telson). Nonsexual characters as in male. Distribution. Known only from the type locality. Etymology. Since the species epithet (Gr., cavicola , “cave-dweller”) is a noun in apposition, its gender does not change with the generic name.

Figures

FIGURES 1–7. Packardesmus cavicola. Fig. 1. Head, antennae, collum and first three rings of male, ventrolateral view. Fig. 2. Head, collum and first four rings of male, dorsal view. Fig. 3. Rings 12 and 13 of male, dorsal view. Fig. 4. Gonopods, ventral view. Fig. 5. Right gonopod, posteroventral view. Fig. 6. Apex of left gonopod, ventral view; s, solenomere, p, pore. Fig. 7. Gonopods, posterior view.