Gerdalbertia Khaustov, Hugo-Coetzee & Ermilov, 2017, gen. nov.

Genus Gerdalbertia gen. nov.

Type species: Gerdalbertia elongata sp. nov.

Diagnosis. FEMALE. Body well sclerotized, distinctly elongate. Prodorsum completely covered by tergite C in living specimens (Fig. 10 A); in mounted specimens anterior part of prodorsum and gnathosoma not covered. Gnathosomal capsule of about equal length and width, dorsally with 2 pairs of cheliceral setae (cha, chb); postpalpal setae present; palps prominent, with 2 pairs of setae (dFe, dGe); tibial claw distinct; palpal solenidion well developed, accessory setigenous structure (ass) large, mushroom-like. Subcapitular setae (m) present. Subcapitulum with 1 pair of oval pits in posterior half. Pharyngeal pumps tripartite, joined together; pump 1 butterfly-like, slightly smaller than oval pump 3, pump 2 large, subrectangular, about 2 times longer than pump 3. Prodorsum with 2 pairs of setae (v 2, sc 2), 1 pair of clavate trichobothria, long stigmata and distinct lateral propodosomal spine. Tergite C subtriangular, not expanded laterally, its anterior margin not thickened; anterior and lateral parts of tergite C with distinct longitudinal striation (Fig. 9 A). Posterolateral parts of prodorsum with unusual pteromorph-like projections, usually folded to ventral surface (Fig. 9 C). Tergite C with 2 pairs of setae (c 1, c 2), setae c 1 situated distinctly anteriorly to c 2; tergite D with one pair of setae (d) and 1 pair of round cupules ia; tergite EF with two pairs of setae (e, f); tergite H with two pairs of setae (h 1, h 2) and 1 pair of round cupules ih; posterior margin of tergite H with short U-shaped process. Coxal fields I with two pairs of setae (1 a, 1 b); coxal fields II with two pairs of setae (2 a, 2 b); coxal fields III with three pairs of setae (3 a, 3 b, 3 c); coxal fields IV with three pairs of setae (4 a, 4 b, 4 c). Pseudanal segment with two pairs of setae (ps 1, 3). Setae ps 2 absent. Setae 2 b not modified, barbed. Apodemes 1 (ap1) well developed, apodemes 2 (ap2) well developed, joined with well developed prosternal apodeme (appr); appr joined with sejugal apodeme (apsej); secondary transverse apodeme (sta) well developed; apodemes 3 (ap3) weakly developed, diffuse, joined with poststernal apodeme (appo); apodemes 4 (ap4) long. Apodemes 5 very short, situated in the space between trochanter IV and setae 4 b. Posterior margin of posterior sternal plate straight. Anterior genital sclerite (ags) bell-like, posterior genital sclerite (pgs) subtriangular. Leg I slightly shorter and thinner than leg II. Tibiotarsus I cylindrical, with simple sickle-like claw situated on distinct pretarsus; unguinal setae completely absent. Seta tc” situated on very short pinnaculum. Seta d of femur I smooth, slightly thickened and pointed. Legs II–III with pair of padded claws and large flipper-like empodium; setae tc’ of tarsi II and III spiniform; claws on tarsus IV very small, simple, empodium very small. Pretarsus IV very long. Femur and genu IV immovably connected. Femora III–IV divided into basi- and telofemur. Leg setation: leg I; tr 1 (v’), fe 3 (d, l’, v”), ge 4 (l’, l”, v’, v”), tita 16(4) (d, l’, l”, v’, v”, k, tc’, tc”, p”, ft’, ft”, pv’, pv”, pl’, pl”, s, ω 1, ω 2, φ 1, φ 2); leg II: tr 1 (v’), fe 3 (d, l’, v”), ge 3 (l’, l”, v’), ti 4(1) (d, l’, v’, v”, φ), ta 6(1) (pl”, tc’, tc”, pv’, pv”, u’, ω); leg III: tr 1 (v’), fe 2 (d, v’), ge 2 (l’, v’), ti 4(1) (d, l’, v’, v”, φ), ta 6 (pl”, tc’, tc”, pv’, pv”, u’); leg IV: tr 1 (v’), fe 2 (d, v’), ge 1 (v’), ti 3(1) (d, l’, v’, φ), ta 6 (pl”, tc’, tc”, u’, pv’, pv”).

MALE. Gnathosomal capsule cylindrical, dorsally with 2 pairs of setae (cha, chb), ventrally with 1 pair of large cylindrical solenidia and 1 pair of subcapitular setae m. Accessory setigenous structure absent. Prodorsum with two sclerites: prodorsal shield and long and narrow sclerite situated between prodorsal shield and gnathosomal capsule. Prodorsal shield with 3 pairs of setae (v 2, sc 1, sc 2). Hysterosoma covered by tergites CD, EF and H. Tergite CD with 3 pairs of setae (c 1, c 2, d) and 1 pair of round cupules ia. Tergite EF with 2 pairs of setae (e, f), tergite H with 2 pairs of setae (h 1, h 2). Coxal fields I with 2 pairs of setae (1 a, 1 b); coxal fields II with 2 pairs of setae (2 a, 2 b); coxal fields III with 3 pairs of setae (3 a, 3 b, 3 c); coxal fields IV with 2 pairs of setae (4 a, 4 c), setae 4 b situated posteriorly to coxal fields IV. Pseudanal segment with two pairs of setae (ps 1, 2). Ap1 completely fused with appr, ap2 well developed, joined with well developed appr; apsej indistinct in central part. Ap3 and ap4 well developed. Apodemes 5 very thick, strongly sclerotized. Aedeagus curved as in other scutacarid mites, but not transversely striated. Leg I slightly longer and thicker than leg II. Tarsus I cylindrical, with simple sickle-like claw situated on distinct pretarsus. Legs II–III each with pair of simple claws and small flipper-like empodium with distinct incision in distal part; leg IV thickened, without claws. Leg setation: leg I; tr 1 (v’), fe 3 (d, l’, v”), ge 4 (l’, l”, v’, v”), ti 6(2) (d, l’, l”, v’, v”, k, φ 1, φ 2), ta 13(2) (tc’, tc”, p”, p”, ft’, ft”, pv’, pv”, pl’, pl”, s, u’, u”, ω 1, ω 2); leg II: tr 1 (v’), fe 3 (d, l’, v”), ge 3 (l’, l”, v’), ti 4(1) (d, l’, v’, v”, φ), ta 7(1) (pl”, tc’, tc”, pv’, pv”, u’, u”, ω); leg III: tr 1 (v’), fe 2 (d, v’), ge 2 (l’, v’), ti 4(1) (d, l’, v’, v”, φ), ta 7 (pl”, tc’, tc”, pv’, pv”, u’, u”); leg IV: tr 1 (v’), fe 2 (d, v’), ge 1 (v’), ti 4(1) (d, l’, v’, v”, φ), ta 6 (pl”, tc’, tc”, u’, pv’, pv”).

LARVA. Gnathosomal capsule in general similar with that of female, but setae chb short and thick; postpalpal setae not evident. Prodorsum with 2 sclerites: prodorsal shield and subrectangular sclerite situated between prodorsal shield and gnathosomal capsule. Prodorsal shield with 3 pairs of setae (v 2, sc 1, sc 2). Tergite C divided into 3 parts; central part with setae c 1; lateral parts with setae c 2. Tergite D with 1 pair of setae (d) and 1 pair of round cupules ia. Tergite EF with 2 pairs of setae (e, f). Segments H and Ps fused into caudal capsule bearing 2 pairs of setae (h 1, h 2) and 1 pair of cupules ih dorsally and 3 pairs of pseudanal setae (ps 1-3) ventrally. Coxal fields I–III with 2 pairs of setae (1-3 a, 1-3 b). Tarsus I with two claws situated on distinct pretarsus. Legs II–III each with pair of simple claws and small flipper-like empodium with distinct incision in distal part. Leg setation: leg I; tr 0, fe 3 (d, l’, v”), ge 4 (l’, l”, v’, v”), ti 6(1) (d, l’, l”, v’, v”, k, φ 1), ta 11(1) (tc’, tc”, ft’, ft”, pv’, pv”, pl’, pl”, s, u’, u”, ω 1); leg II: tr 0, fe 3 (d, l’, v”), ge 3 (l’, l”, v’), ti 4(1) (d, l’, v’, v”, φ), ta 7(1) (pl”, tc’, tc”, pv’, pv”, u’, u”, ω); leg III: tr 0, fe 2 (d, v’), ge 2 (l’, v’), ti 4(1) (d, l’, v’, v”, φ), ta 7 (pl”, tc’, tc”, pv’, pv”, u’, u”).

Differential diagnosis. Females of the new genus are most similar to Imparipes Berlese, 1903, in having 5- segmented legs IV, long and narrow pretarsus IV bearing small claws, similar shape of pharyngeal pumps, well developed lateral propodosomal spine, long stigmata, and well developed palpal solenidion. The new genus differs from Imparipes by the elongate body shape (vs. round in Imparipes), absence of well developed pinnaculum on tibiotarsus I (vs. tibiotarsus I always with well developed pinnaculum bearing 2 setae in Imparipes). Females of the new genus differ from all known genera of Scutacaridae by the immovably connected femur and genu IV (vs. movably connected in other Scutacaridae) and by the presence of pteromorph-like structures laterally to tergite C (vs. unknown in other Scutacaridae). Males of the new genus are most similar to Imparipes, Archidispus Karafiat, 1959 and Heterodispus Paoli, 1911 by the absence of an accessory setigenous structure on the gnathosomal capsule (Ebermann 1994; Jagersbacher-Baumann & Ebermann 2016). The new genus differs from all these genera by the smooth (non striated) aedeagus (vs. always striated in Imparipes, Archidispus and Heterodispus).

Species included. The genus Gerdalbertia includes one species, G. elongata sp. nov.

Distribution and habitat. Gerdalbertia elongata sp. nov. inhabits nests of and is phoretic on termites Trinervitermes trinervoides (Sjostedt, 1911) in South Africa.

Etymology. The new genus is named in honour of the late German acarologist Gerd Alberti, for his outstanding contributions to Acarology.