Hexacaudalges Mironov and Proctor, 2005

Mironov, S. V. & Proctor, H. C., 2005, A new feather mite genus of the family Psoroptoididae (Acari: Analgoidea) from cassowaries, Journal of Natural History 39 (37), pp. 3297-3304 : 3298-3301

Genus Hexacaudalges Mironov and Proctor , gen. n.

Type species: Megninia casuaricola Proctor, 2001 .

Diagnosis

Both sexes. Prodorsal shield a long and narrow plate, attenuate towards anterior end, not encompassing scapular setae se, si ( Figures 1a , 3a ). Setae vi absent. Laterocoxal setae scx absent. Tarsi I, II without ventral process ( Figures 2a–d , 4a–b ). Tibiae I, II with short and rounded ventral process. Posterolateral angle of femora I without acute indentation.

Male. Epimerites I fused into a Y. Epimerites II not connected to epimerites III, coxal fields II and III open. Opisthosoma with well-developed opisthosomal lobes; each split into three very long and narrow branches ( Figure 1a, b ): inner branches straight, with bifurcate apex and bearing setae ps1 between this bifurcation; outermost branches slightly curved, with acute apex, and bearing subapical setae f2; intermediate branches with acute apex, with setae h3 situated subapically, and setae h2 and ps2 at mid-level of the lobes. Genital apodemes as a short inverted U, genital apparatus very small, aedeagus shorter than genital arch. Adanal apodemes absent, small adanal shields anterior to setae ps3 present. Tarsi I, II with two claw-like ventral setae: s— bifurcated apically, la —with single apex on tarsus I and bifurcated apically on tarsus II ( Figure 2a–d ). Legs III hypertrophied. Distal end of tibia III with short paraxial and antaxial spurs. Tarsus III with small apical spine; setae s, w lanceolate, moved to the base of this segment ( Figure 2e ). Tarsus IV greatly reduced, much shorter than tibia, with one dorsal spine, with setae seta e, d modified into tarsal suckers ( Figure 2f ).

Female. Epimerites I free. Hysteronotal shield absent. Posterior end of opisthosoma with two pairs of macrochaetae h2, h3. Copulatory opening situated dorsally, distant from posterior margin of opisthosoma ( Figure 3a ). Epigynium bow-shaped, small, separated from epimerites, with setae 3a on its tips ( Figure 3b ). Tarsi I, II with all setae setiform ( Figure 4a, b ); ambulacral stalk of tarsi III, IV with ventral spine-like extension ( Figure 4c, d ).

Differential diagnosis. The new genus is referred to the subfamily Psoroptoidinae (see Discussion), but clearly differs from all other genera of the subfamily by the following characters. In both sexes, the prodorsal shield is narrow and does not encompass bases of scapular setae se, si; in males, setae s and la of tarsi I, II are claw-like, setae s and w of tarsi III lanceolate, opisthosoma with well-developed opisthosomal lobes split into three very long and narrow branches; in females, all setae of tarsi I, II setiform, hysteronotal shield absent.

In both sexes of other known psoroptoidine genera ( Gaud and Atyeo 1967, 1982b, 1996), the prodorsal shield is trapezoidal and encompasses (or at least touches) the bases of the scapular setae, and tarsi I and II are similar in males and females and carry one claw-like 3300 seta s. In males of other psoroptoidids, setae s, w of tarsi III are setiform, and opisthosomal lobes are not split into branches. Females of other genera always have hysteronotal shields.

The genus includes only the type species, Hexacaudalges casuaricolus ( Proctor, 2001) , comb. n.

Etymology

Contraction of hexa (L., six), cauda (L., tail) and the common combining form ‘‘ alges ’’ to reflect the unique structure of the opisthosoma in males, and placement of the genus in the superfamily Analgoidea .

Figures

Figure 1. Hexacaudalges casuaricolus, male. (a) Dorsal view; (b) ventral view.

Figure 2. Hexacaudalges casuaricolus, leg segments of male. (a) Tarsus I, dorsal view; (b) same, ventral view; (c) tarsus II, dorsal view; (d) same, ventral view; (e) tibia and tarsus III, dorsal view; (f) tibia and tarsus IV, dorsal view, paraxial aspect. Scale bars: A (a–e); B (f).

Figure 3. Hexacaudalges casuaricolus, female. (a) Dorsal view; (b) ventral view.

Figure 4. Hexacaudalges casuaricolus, tarsal segments of female, dorsal view. (a) Tarsus I; (b) tarsus II; (c) tarsus III; (d) tarsus IV.