Nodocepheus, Hammer, 1958

Colloff, Matthew J., 2022, First records of Tumerozetidae and Nodocepheidae from Australia, with descriptions of new taxa and a re-assessment of the Polypterozetoidea (Oribatida, Brachypylina), Zootaxa 5194 (1), pp. 33-57 : 44

Redefinition of Nodocepheus

Definition. Polypterozetoid mites with subcapitulum secondarily anarthric ( Figure 5b ) or diarthric, though the labiogenal articulation may be incomplete ( Figure 7d ); rutellum bifurcate, apex Y-shaped ( Figure 4g ); chelicerae modified: either with digitus fixus pointed, lacking teeth and digitus mobilis comb-like ( Figure 4e ) or both digits with reduced, blunted teeth, offset from each other ( Figure 4l ). With serrated tutorium and cusped sub-tutorium. With short, rounded single-lobed or bilobed humeral processes. With 11 pairs of smooth notogastral setae positioned marginally; c 1 and c 2 marginal, on or near humeral process, sometimes on ventral fold. With five pairs of genital setae. Epimeral setal formula 3-1-3-3. Genital setae 6 pairs; aggenital setae 1 pair, anal setae 2 pairs, adanal setae 3 pairs. Legs monodactylous.

Remarks. The above definition is based on those of Piffl (1972) and Woas (2002). Mahunka (1983) provided a key to the six species of Nodocepheus known at that time, stressing the morphology of the humeral lobe, bothridial seta, tutorium and sub-tutorium.

The presence of Trägårdh’s organ is based on the examination by Piffl (1972) of a single specimen of Nodocepheus dentatus Hammer 1958 in which the chelicerae were damaged. The structure is described as short, broad and thus lacks the characteristic elongated form of this structure. I could not identify a Trägårdh’s organ on the chelicerae Nodocepheus luxtoni sp. nov.

In Nodocepheus dentatus , N. laterodentatus Piffl, 1972 and N. luxtoni sp. nov., setae c l are shifted laterally to the humeral region, positioned on a fold of the humeral process adjacent to setae c 2 ( Piffl 1972, Plate 13 therein; Figure 5a herein). It is likely that N. barbatus Hammer, 1966 (originally described as N. dentatus var. barbatus ) shares this character state, giving a likely notogastral setal complement of 11 pairs (cf. Piffl 1972, p. 292), rather than 9 pairs as illustrated by Hammer (1966, Figure 85 therein). In N. minimus Mahunka, 1985 , setae c 1 appear to be absent and c 2 are apparently reduced to their alveoli, giving a complement of 10 pairs (including c 2). In N. cerebralis Mahunka, 1980 and N. hammerae Balogh, 1961 neither of the c series are illustrated, yet in the figures of the humeral regions of N. baloghi Mahunka, 1983 , N. cerebralis , N. dentatus and N. hammerae by Mahunka (1983, Figures 47-53 therein), c 1 is present on the ventral surface of the median lobe of the humeral process, as illustrated for N. dentatus by Piffl (1972, Plate 13, Figure Nd 3 therein). It seems likely that c 2 is also present in N. cerebralis , N. hammerae , and N. minimus on the anterioventral surface of the rugose lateral lobe of the humeral process, but has been overlooked when viewed dorsally because of its position below the heavily textured surface of the lobe.

Figures

FIGURE 4. Sacculella yarra gen. et sp. nov. (a) palp; (b) chelicera; (c) digitus mobilis of chelicera, ventral aspect; (d) tutorium and sub-tutorium. Nodocepheus luxtoni sp. nov. (e) chelicera; (f) palp; (g) apex of rutellum; (h) tutorium and sub-tutorium; (i) rostrum and rostral setae; (j) Polypterozetes cherubin Grandjean, 1959, chelicera; (k) Podopterotegaeus miyamaensis Fujikawa, 2008, chelicera; (l) Nodocepheus dentatus Hammer, 1958, chelicera. Scale bars: a, b, d, e, f, h = 20 μm; i = 10 μm; c, g = 5 μm

FIGURE 5. Nodocepheus luxtoni sp. nov. (a) dorsal aspect; (b) ventral aspect; (c) lateral aspect. Scale bar = 100 μm

FIGURE 7. Morphology of the subcapitulum of polypterozetoid taxa included in the character analysis. (a) Polypterozetes cherubin Berlese 1916; (b) Podopterotegaeus altimonticola Piffl, 1972; (c) Nemacepheus dentatusAoki, 1968; (d) Nodocepheus laterodentatus Piffl, 1972; (e) Tumerozetes roughleyi sp. nov.; (f) Sacculella yarra gen. et sp. nov.