Sacculella yarra, 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 : 41-44

Sacculella yarra sp. nov.

( Figures 3 , 4 )

Dimensions. Holotype male length 302 μm, breadth 208 μm. Paratypes: male: length 300 μm, breadth 217; females (n = 3) 327 μm (range 323–330 μm); mean breadth 244 μm (range 236–252 μm). Ratio of prodorsum to total length: 0.58 (holotype).

Adult. Prodorsum: rostrum broad in dorsal view, almost covered by broad, apically rounded lamellae, extending from apex of rostrum to bothridia and diverging posteriolaterally and with a faint, short ventral translamella ( Figure 3a ). With short, smooth rostral setae (ro), only visible in lateral view ( Figure 3c ). Lamellar setae (le) smooth, emerging from ventral surface of lamellae, only visible in ventral view ( Figure 3b ). Interlamellar seta (in) welldeveloped, positioned anteriomedially of bothridium. Bothridium well-developed, cylindrical, with sclerotized rim and internal circular thickening. Bothridial setae elongated, setiform, with faint spinose ornamentation; extending posteriorly as far as bases of setae c 1. Lateral region of prodorsum posterior of bothridium strongly concave.

Notogaster: Margins of humeral processes (h) convex laterally, then slightly concave anteriorly, extending as far as bothridia, medially with thin cuticle with polygonal alveolate microsculpture and dorsal V-shaped keels, forming sacculate structures covering lateral parts of prodorsum ( Figure 3a ). Notogaster smooth, U-shaped, broader (216 μm; holotype) than long; with 11 pairs of marginal setae (c 1, c 2 plus l, h and p series); l, h and p series ornamented with fine spines basally and borne on faint lateral region of more heavily sclerotized cuticle. Setae c 1 and c 2 smooth, well developed, positioned laterally and adjacent on humeral process. Dorsosejugal furrow transverse, heavily sclerotized, overhanging prodorsum. Lyrifissurae ia present.

Ventral aspect: apex of subcapitulum in form of broad, inverted V, with tectum derived from genae, bearing a median infrabuccal cleft (ibc) on its ventral surface ( Figure 8f ); short, setiform setae a and m with bases not hidden by tectum in ventral orientation; setae h short, spiniform, positioned anteriolaterally, immediately posterior of setae m. Labiogenal articulation absent. Rutellum Y-shaped ( Figure 3c ). Chelicerae short, with digitus fixus reduced to flat, smooth, lobe-like scale, with tooth kk present; digitus mobilis curved, almost as long as digitus fixus, bearing a comb-like fringe of several thin teeth ( Figures 4b, 4c ). 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 4a ). Tutorium with 4-5 short spines, sub-tutorium with cup-shaped invagination and acute point ( Figure 4d ).

Epimeral plates discrete, all broadly separated in midline and from each other, sub-rectangular; epimeral setation 2-1-2-3 ( Figure 3b ). Pedotectum I and II relatively weakly developed; patronium present; discidium (di) with prominent, sharp point; well-developed circumpedal carina (cc) present. Ventral plate sub-circular, broader than long. Genital and anal plates each surrounded by ring of sclerotized cuticle; genital plates 36 µm long, with 4 pairs of setae; 1 pair of aggenital setae positioned posteriorly level with preanal organ (po), 2 pairs of adanal setae and 2 pairs of anal setae; lyrifissure iad in para-anal position ( Figure 3b ). Anal plates lozenge-shaped, 53 µm long; only slightly separated from genital plates. Preanal organ broad, flat T-shaped.

Lateral aspect: Rostrum straight, vertical, almost square; tutorium pointed apically; pedoctectum I and II rounded apically; discidium prominent, pointed ( Figures 3b, 3c ). Lamellae projecting as far as dorsal apex of rostrum, markedly elevated immediately anterior of bothridia. Interlamellar seta (in) projecting vertically. With a small, blunt, triangular lobe (bl) posterior of bothridium. Humeral processes covering prodorsum between bothridium and dorsosejugal furrow, posterior prodorsum strongly invaginated and overhung by anterior notogaster. Notogaster markedly deeper than long.

Legs: monodactylous; claw lacking dorsal tooth.

Type designation, material examined and locality data. Holotype male, paratype female, wet moss, Cumberland Creek Valley, Marysville-Woods Point Rd, near Cambarville , Yarra Ranges National Park , Victoria, 37º33’S 145º53’E, coll. R. E. Roughley, 12.iii.1996 . Paratypes: one female, one male, ANIC 297 , moss and litter, rainforest with Nothofagus cunninghami , near picnic area at Cumberland Memorial Reserve, Cumberland Creek Valley, Yarra Ranges National Park , Victoria. 37°34’S 145°52’E, 920 m. Coll. R. W. Taylor and R. J. Bartell, 4.xi.1970 .

Etymology. This species is named for its type locality in the Yarra Ranges, Victoria.

Diagnosis. Sacculella yarra sp. nov. can be distinguished from all other species in the genus by the following combination of characters: (1) the lamellae broad, converging anteriomedially, with setae le positioned ventrally; (2) the bothridia prominent, internally ridged; bothridial setae elongated, setiform, smooth; (3) the humeral processes large, convex, covering lateral regions of prodorsum; (4) the presence of a patronium; (5) the rounded notogaster, considerably broader than long, with 11 pairs of marginal setae.

Remarks. The shared character states between Sacculella yarra gen. et sp. nov. and Tumerozetes were outlined above in the remarks section on the description of Sacculella gen. nov. However, Sacculella yarra sp. nov. lacks the interlamellar plates, the paired median longitudinal notogastral ridges and the anteriomedian projection of the notogastral plate of Tumerozetes spp. ; it has 4, rather than 5-6 pairs of genital setae; broad lamellae with ventral lamellar setae, rather than narrow pointed ones with the lamellar setae apical; the humeral process are in the form of massive, convex plates, rather than small curved projections; the tutorium is serrated, rather than smooth; pedotectum I is weakly developed with a rounded apex, rather than well developed and pointed; the palptarsus has 8 setae, rather than 9 and the epimeral setal formula is a bi-deficient 2-1-2-3, rather than the holotrichous 3-1-3-3. Other than dimensions, there were no obvious external morphological differences between males and females.

Figures

FIGURE 3. Sacculella yarra gen. et sp. nov. (a) dorsal aspect; (b) ventral aspect; (c) lateral aspect. Scale bar = 100 μm

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 8. Notogastral morphology of polypterozetoid taxa included in the character analysis. (a) Polypterozetes cherubin Berlese 1916; (b) Podopterotegaeus tectus Aoki, 1969; (c) Podopterotegaeus miyamaensis Fujikawa 2008, detail of humeral region; (d) Nemacepheus dentatus Aoki, 1968; (e) Nodocepheus minimus Mahunka 1985; (f) Tumerozetes bifurcatus Hammer, 1966; (g) Sacculella yarra gen. et sp. nov.