Nodocepheus luxtoni, Colloff, 2022

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 : 45-46

Nodocepheus luxtoni sp. nov.

( Figures 4 , 5 )

Dimensions. Holotype length 204 μm, breadth 117 μm. Paratype male: length 192 μm, breadth 113 μm. Paratype females: mean length (n = 11) 211 μm (range 199–221 μm); mean breadth 125 μm (range 113–132 μm). Ratio of prodorsum to total length: 0.41 (holotype).

Adult. Prodorsum: rostrum bluntly point in dorsal view, with short rostral setae on short tubercles, linked by short, transverse ridge ( Figure 4i ). Broad lamellae extending to just posterior of rostrum, with strongly incurved apical cusps at right angles to the rest of the lamellae, bearing short, smooth, setiform lamellar setae (le) and with well-developed translamella ( Figure 5a ). Short, smooth interlamellar setae (in) positioned on centrodorsal region. Bothridium well-developed, cylindrical, with broad sclerotized rim and internal circular thickening. Bothridial setae elongated, club-shaped, with strong spinose ornamentation apically.

Notogaster: humeral processes (h) well-developed, abutting bothridia, with large, elongated lateral lobe bearing short, setiform seta c 1 and smaller medial lobe bearing seta c 2; lateral lobe extending to point posterior of base of seta la ( Figure 5a ). Humeral processes smooth, not ornamented or sculpted. Notogaster smooth, ovoid, longer (216 μm; holotype) than broad; with 11 pairs of smooth, setiform setae positioned marginally (c 1 and c 2 plus l, m and p series); l and h series on short, squat tubercles. Dorsosejugal furrow transverse; with faint, incurved ridges on anteriomedian region of notogaster.

Ventral aspect: subcapitulum secondarily anarthric, with tectum derived from genae, bearing median infrabuccal cleft (ibc) on its ventral surface ( Figure 5b ); short, setiform setae a and m with bases not hidden by tectum in ventral orientation; setae h short, spiniform, positioned just posteriomedially of setae m. Labiogenal articulation absent. Rutellum Y-shaped ( Figure 4g ). Chelicerae with digitus fixus pointed, smooth; digitus mobilis comb-like with sparse, fine teeth ( Figure 4e ). Palp setal formula 0-2-1-3-8; all setae smooth. Eupathidia not on prominent tubercles; eupathidium acm not fused with solendidum ω which is positioned posteriorly on palptarsus ( Figure 4f ). Tutorium well-developed, with a long apical tooth and 4 short teeth; sub-tutorium with blunt cusp ( Figure 4h ).

Epimeral plates I fused in mid-line, others discrete, broadly separated in midline and longitudinally; plates I and II sub-rectangular, III and IV oval; epimeral setation 3-1-3-2 ( Figure 5b ). Pedotectum I and II large, prominent, with pointed anterior and posterior lobes; discidium (di) broad, well-developed, pointed. Perigenital carina present, bearing enantiophysis E4. Ventral plate ovoid, markedly longer than broad. Genital and anal plates each surrounded by ring of sclerotized cuticle; genital plates 33 µm long (holotype), with 5 pairs of setae; 1 pair of aggenital setae positioned just posterior of genital plates; 3 pairs of adanal setae, 2 pairs of anal setae; lyrifissure iad in para-anal position ( Figure 5b ). Anal plates lozenge-shaped, 41 µm long (holotype); separated some distance from genital plates. Preanal organ broad, flat T-shaped.

Lateral aspect: Rostrum straight, vertical; tutorium (tu) and sub-tutorium (stu) each with acute point, tu strongly serrated dorsally; pedoctectum I and II pointed rounded apically; discidium leaf-shaped, bluntly pointed ( Figure 5c ). Lamellae projecting as far as dorsal apex of rostrum. Exobothridial seta (ex) present. Anterior notogastral margin overhanging prodorsum.

Legs: monodactylous; claw with a dorsal tooth.

Type designation, material Examined and Locality Data. Holotype female and five paratype females, moss on Sassafras ( Atherosperma moschatum ), cool temperate rainforest, 1077 m., Errinundra Saddle, Errinundra National Park , Victoria, 37°19’S 148°51’E, 1030 m., coll. M.J. Colloff, 29.ix.2009 . Paratype: female, ANIC 3757 , sifted litter and mossy logs, rainforest with Eucalyptus sp. , State Forest, 2.2 km north-east of Corinna , Tasmania, 41°39’S 145°06’E., 45 m., coll. T. Weir and C. Lemann, 14.iii.2008 . Paratype: female, TAS-183 Litter, eucalypt forest, Old Farm Road, Mount Wellington, Tasmania, 42°54’S 147°14’E, coll. P. Greenslade, 20.vi.1989 . Paratypes: four females, moss, Nothofagus cunninghami rainforest, rainforest walk, Maits Rest, Otway National Park , Victoria, coll. M.J. Colloff, 19.vii.2011 .

Etymology. This species is named in honour and memory of my friend and colleague, the late Dr Malcolm Luxton, in recognition of his contribution to our understanding of the taxonomy and biogeography of the oribatid mites of the Australasian region.

Diagnosis. Nodocepheus luxtoni sp. nov. can be distinguished from all other species in the genus by the following combination of characters: (1) most of the notogastral setae are on squat tubercles; (2) with the epimeral setal formula 3-1-3-2; (3) the very large, pedotecta I and II with an indented apex, appearing shallowly bifurcate; (4) the prominent, smooth, elongated lateral lobe of the humeral process, extending to a point posterior of base of seta la; (5) the broad, discidium, bluntly pointed; (6) the rostral setae on short tubercles, linked by a short, transverse ridge; (7) the strongly incurved and opposing lamellar cusps (8) the smooth, short setae le positioned sub-apically on the lamellar cusps; (8) the bothridial seta with a long stalk, the head club-shaped and covered in long, well-developed spinules; (9) the tutorium with a long apical tooth and 4 short teeth and the sub-tutorium with a blunt cusp.

Remarks. Mahunka (1983, p. 164) stated that of the six species described by that time, all of them except N cerebralis “stand very near to each other” and that, based on an examination of types, they could only be distinguished by the morphology of the humeral processes, tutorium and sub-tutorium, with chaetotaxy and the morphology of the sensillus considered as secondary characters. Nodocepheus luxtoni sp. nov. belongs to a group with N. baloghi and N. minimus that share the following character states: (1) the bothridial seta has a long stalk and a club-shaped head densely ornamented with well-developed spines and (2) the humeral process is large, expanded and extends from the bothridium to a position at least as far posteriorly as the level of the base of setae la. However, N. baloghi and N. minimus both have setae le with spinose ornamentation, rather than smooth, and are positioned apically on broad lamellar cusps, rather than sub-apically on narrow, strongly incurved cusps.

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