Neoeutegaeus malcolmi, Colloff, 2023

Colloff, Matthew J., 2023, The oribatid mite superfamily Eutegaeoidea (Acari, Oribatida), with descriptions of new taxa from Australia and New Caledonia and a re-assessment of genera and families, Zootaxa 5365 (1), pp. 1-93 : 48-50

Neoeutegaeus malcolmi sp. nov.

( Fig. 24 )

Dimensions. Holotype female length 280 μm, breadth 186 μm, paratype females (n = 16) length 278 μm (range: 271–292 μm), breadth 175 μm (range: 166–193 μm); paratype males (n = 4) length 265 μm (range: 263–267 μm), breadth 162 μm (range: 160–164 μm). Ratio of prodorsum to total length (holotype): 0.48.

Description of adult. Prodorsum: rostrum acute; rostral setae (ro) short, straight, smooth, not visible in dorsal aspect. Lamellae broad, very long, almost half body length, extending well beyond rostrum, separated medially, lateral margins convex ( Fig. 24a ). Lamellar seta (le) short, curved medially, smooth, emerging from alveolus on anterior margin of cone-shaped lamellar cusp; medial margins of cusps convex, with complete translamella. Interlamellar setae (in) minute, close together. Bothridia elongate, corniculate, projecting laterally beyond inner margins of humeral processes, openings angled anterolaterally. Bothridial seta long, head club-shaped, apex rounded, smooth.

Notogaster: ratio of length to breadth: 0.82; notogaster rounded, convex. Humeral processes very long, as long as lamellae, straight, parallel, triangular, pointed, extending to point just posterior of translamella, lateral margin expanded where process joins anterolateral margin of notogaster forming slight projection ( Fig. 24a ). Lyrifissures ia and im short. With eight pairs of notogastral setae, l series and h 2 and h 3 sub-marginal, smooth, short, sub-equal in length, stout, covered in cerotegument; p series very short, not visible in dorsal aspect.

Ventral aspect: subcapitulum acute; subcapitular setae extremely short, sub-equal in length, smooth ( Fig. 24b ). Tutorium very broad, pointed. Epimeral plates discrete, broadly separated in midline, sub-rectangular to ovoid, plates III and IV much shorter than I and II; with median strip of dumbbell-shaped cuticle between plates I and II; epimeral setation 3-1-2-2; setae very short, sub-equal in length. Pedotectum I (pd I) well-developed, rectangular, with blunt anterior apex; pd II very long, broad, lateral margin sloped obliquely; discidium broad, pointed apically; perigenital carina and enantiophysis E4 present. Ventral plate ovoid, markedly broader than long. Genital and anal plates separated by distance of half length of genital plates; genital plates 36 µm long, with five pairs of short setae sub-equal in length, aligned longitudinally; two pairs of extremely short adanal setae; lyrifissure iad in para-anal position, some distance from margin of anal plate, about same as distance from plate as bases of setae ad 2. Anal plates ovoid, 41 µm long. Pre-anal organ (po) oval.

Type designation, material examined and locality data. Holotype female, ANIC accession no. 53-1063, ANIC 3751 , sieved litter and mossy logs, rainforest with Eucalyptus sp. , Lyrebird Nature Walk, 3.3 km south-east of Mount Field, Mount Field National Park , Tasmania, 42°41'S, 146°40'E, 690 m., coll. T. Weir and C. Lemann, 8.iii.2008 . Paratypes: 12 females, three males, ANIC accession no. 53-10064, ANIC 3757 , sifted litter and mossy logs, rainforest with Eucalyptus sp. , State Forest , 2.2 km NE Corinna, Tasmania, 41°38’43”S 145°05’50”E, 45 m ., coll. T. Weir & C. Lemann, 14.iii.2008 . Paratype female, ANIC accession no. 53-1065, ANIC 666 , litter and rotting log debris, Nothofagus cunninghami rainforest, Mount Field National Park , Tasmania, 42°41'S, 146°43'E, 160–240 m., coll. J. Lawrence & T. Weir, 30.i.1980 . Paratypes: four females, one male, ANIC accession no. 53-1066, TAS-183, litter, Eucalyptus forest, Old Farm Road, Mount Wellington, Tasmania, 42°54'S, 147°14'E, coll. P. Greenslade, 20.v.1989 .

Etymology. This species is named in honour and in memory of my friend and colleague, the late Dr Malcolm Luxton, formerly of the Department of Biology, Liverpool John Moores University and National Museum of Wales, Cardiff, in recognition of his substantial contribution to the systematics, taxonomy and ecology of oribatid mites.

Diagnosis. Neoeutegaeus malcolmi can be distinguished from other species in the genus by the following combination of characters: (1) the narrow, acute, cone-shaped lamellar cusps lacking teeth,; (2) the short, smooth lamellar setae; (3) the minute interlamellar setae; (4) the prodorsum almost as long as the notogaster; (5) the long, club-shaped bothridial setae with smooth head; (6) the large, curved pedotecta II with straight, oblique margins folded dorsally; (7) the broad, pointed discidium; (8) the epimeral setal formula 3-1-2-2.

Remarks. Neoeutegaeus malcolmi shares with N. torsteini the lamellar seta emerging from the apex of the free lamellar cusp, but in N. malcolmi the cusps are cone-shaped and relatively long, whereas in N. torsteini they are sub-triangular, shorter and broader.

Figures

FIGURE 24. Neoeutegaeus malcolmi sp. nov., adult (a) dorsal aspect; (b) ventral aspect. Scale bar = 100 μm.