Opionoides cataracta Shear & Marek 2025, new species
Creators: name: Shear, William A.
name: Marek, Paul E.
Publisher: name: Zenodo
Year: 2025
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Diplopoda
Chordeumatida
Caseyidae
Opionoides
Opionoides cataracta

description: Opionoides cataracta Shear & Marek, new species.
Figs 22–29, 32
Types. Male holotype, three male and two female paratypes from Golden and Silver Falls State Natural Area, 43.483°N, - 123.933°W, 96 m asl, Coos Co., Oregon, collected 27 May 2007 by C. Richard & A. Fusek. Parts of paratype males are mounted on SEM stub WS 38-5.
Etymology. The species epithet, a Latin noun in apposition, “waterfall,” refers to the type locality.
Diagnosis. As for the genus.
Description. Male paratype. Length about 10 mm, width 1.0 mm. 30 rings (Fig. 32). Twenty-four ommatidia in triangular eyepatch.
Color pale tan, heavily marked anteriorly and dorsally with purplish brown, pale tan areas around segmental setae.
Segmental setae in straight row across posterior margin of metazonites.
First legpair (Fig. 22) short, stout, with few flattened, spiral setae distal on femur, postfemur and tibia; tarsus with setal comb.
Second legpair (Fig. 23) with gonapophyses (g) distally attenuate, curved, with long setae anteriorly, vas deferens and accessory pore not observed; telopodites (t2) with five podomeres, as long as or slightly longer than gonapophyses, femora elongate.
Third legpair (Fig. 23) coxae (cx3) with narrow lobes slightly curved inward, setose, prominent tuft of apical setae. Third legpair telopodites with five podomeres, prefemur (pf3) strongly expanded, flattened, tarsus minute.
Lepairs four to seven not enlarged.
Gonopods in lateral view (Fig. 24) with anterior angiocoxite (aac) broad, curved, bearing distal crown of many acute spines, not setae (Fig. 26); posterior angiocoxite (pac) large, spiculate, sheathing at least four flagellocoxites (f); colpocoxite (cc) saclike, weakly sclerotized. In mesal view, posterior angiocoxite (pac) projecting anteriorly between anterior angiocoxites, bearing many feathery branches and spicules; small fimbriate branch may represent vestigial telopodite (t).
Ninth legpair (Fig. 28) with coxae (cx3) having posterior humps and coxal processes with widely separated branches (cp); lateral branch short, stout, flattened, mesal branch longer, narrow, curved anteriorly. Ninth leg telopodites of single article but with deep sulcus that appears to divide them, deeply excavate mesally.
Tenth legpair (Fig. 29) with broad sternum (s10), coxae (cx10) elongate, with stout distal, curved processes (cp), large coxal glands (cg); telopodites (t10) reduced.
Paratype female. Length about 11.0 mm, width 1.0 mm. Nonsexual characters as in male. Vulvae not modified.
Records. Known only from the type locality.
Notes. The pregonopodal leg modifications of this species are similar to those of Opiona species and related caseyid genera. However, the gonopods are unusual and unique, due to the spines crowning the distal crest of the anterior angiocoxite and the feathery branches of the posterior angiocoxite. While these branches may recall similar structures on the gonopods of ochrogrammatines, in detail they are very different and probably represent a parallel or convergent development. Unlike the foregoing genus, colpocoxites are present, as well as a small branch which may represent a vestigial telopodite. In addition, there are at least four and perhaps more flagellocoxites, which are a feature of Opiona gonopods, but not those of Paropiona. These are sheathed in the posterior angiocoxite as is the case in Opiona. The ninth legpair is also closer to the Opiona pattern, rather than Paropiona, with rather button-like telopodites. As noted by Gardner and Shelley (1989), some species of Opiona have a prominent sulcus in the single telopodite podomere of the ninth legpair which can give the impression that two podomeres are present instead of just one, and this is the case for Opionoides cataracta, sp. nov. The elongate coxae of the tenth legpair are not found in any Opiona species we have examined, but we have not seen them all.
description: Published as part of Shear, William A. & Marek, Paul E., 2025, Additions to the millipede family Caseyidae Verhoeff, 1909. IV. Two new genera and three new species (Chordeumatida, Striarioidea, Caseyidae), pp. 533-547 in Zootaxa 5631 (3) on pages 543-546, DOI: 10.11646/zootaxa.5631.3.7, http://zenodo.org/record/15371308