Punkochyzeria khoyi sp. nov.

(Figs. 10, 11, 17J, 18I, Table 2)

Diagnosis. Long dorsal setae of two kinds: 1) ciliated, moderately rigid, with length of cilia at least three times the width of setal shaft (Fig. 17J), uniform throughout entire length of seta and 2) thick, rigid, spine-like. Posterior part of opisthosoma with long ciliated setae (Figs. 10A, B). Odontus relatively slender (its base smaller than width of palptarsus), on tibial projection (Figs. 10I, 18I). Palp tarsus approx. twice longer than odontus (Figs. 10I, 18I). Ctenidium of 5 spinose setae (Fig. 18I). Dorsal integument of opisthosoma reticulated (Fig. 11).

Type material. Holotype PIN 5608 /345a.

Occurrence and geological age. Mid-Cretaceous amber, Hukawng Valley, Kachin State, northern Myanmar.

Type deposition: Borissiak Paleontological Institute, Russian Academy of Sciences.

Description

Holotype, PIN 5608/345a (ex. IM-1310). Postlarval stage, incomplete (lacks ventral surface of opisthosoma) but otherwise well-preserved specimen, almost fully impregnated with fossil resin and transparent (Fig. 10), with large air bubble obscuring idiosoma ventrally (but opened and cleared during preparation) and a few smaller air bubbles at bases of legs. Idiosoma (length 2150, width 1200) markedly widened behind aspidosoma/opisthosoma border and surrounded with cuticular rim, dorsally with four short rounded projections, each holding a tuft of long setae (Fig. 10A). All four tufts of long setae pressed to idiosoma dorsum and projected posteriorly. Chelicera not visible, hidden under hypostome. Hypostome long, narrow (Fig. 10I, J), chaetotaxy not resolved, setae not longer than twice the width of hypostome. Palps relatively slender (Figs. 10I, J, 18I). Palp tibia with odontus on long tibial projection, without paradont. Dorsally on palptibia row of five spinose setae (ctenidia) (Fig. 18I, arrows). Palp tarsus oval, elongate, with numerous short setae, ca. twice the length of odontus. Setae on palp strong with short sparse barbs or some simple setiform setae on palptibia.

Aspidosoma clearly delimited, triangular in outline (Fig. 10D). Crista metopica with two pairs of trichobothria (Fig. 10G). ASA extended into anterior, triangular process. PSA oval in outline, with indistinct posterior process. Bothridia of posterior sensilla (PSens) larger than anterior sensilla (ASens). Eyes located laterally to crista metopica, at level of posterior sensilla, anterior lens slightly larger than posterior one (Fig. 10E).

Long dorsal setae originating from four dorsal projections of two types: 1) numerous very long, ciliated, moderately rigid, length of cilia at least three times the width of setal shaft (uniform throughout entire length of seta) (Fig. 17J), varying in length, longest 1900, ratio to idiosomal length 0.83; 2) slightly shorter, thicker, rigid, spine-like, without cilia, with small irregularities. Other idiosomal setae: 3) numerous long (680–740), densely ciliated, located in posterior part of opisthosoma (Fig. 10A, B) and in anterior part of aspidosoma (Fig. 10D); 4) numerous moderately long, 3–7 times shorter than (3), ciliated, located in lateral part of opisthosoma (Fig. 10F) and on aspidosoma, absent on dorsal surface of opisthosoma. Dorsal integument of opisthosoma distinctly reticulated with irregular cells of polygonal shape and lacks dense setation (Fig. 11).

Legs moderately robust. Legs I and IV longer than II and III, and a little longer than idiosoma (Fig. 10A, B). Legs I with slightly wider segments than other legs. Leg segments covered with numerous setae of different kinds: ciliated, barbed or smooth (Figs. 10K–M). Tarsi II–IV long, each terminates with paired claws of similar size and shape (Figs. 10L, M), tarsus I slightly shorter, with pair of shorter claws (Fig. 10K), empodium not resolved.

Larva: unknown.

Etymology. Punkochyzeria khoyi sp. nov. is named after Yuri N. Klinskikh (1964–2000), also known as “Yuri Khoy”, a Russian musician, singer and a founder of the punk-rock band “Sektor Gaza”.

Remarks. The absence of the ventral portion of the opisthosoma, in conjunction with the bubble's interaction with its dorsal aspect from within the mite, engendered a distinctive opportunity to examine the dorsal cuticle, which would have otherwise remained concealed beneath the tufts of protracted dorsal setae. Upon opening the bubble during the preparation of the amber specimen, it was observed that portions of the dorsal cuticular wall of the opisthosoma had exfoliated from the amber. These fragments were meticulously extracted and mounted individually, with the external side exposed for subsequent analysis using SEM and CLSM.

Imaging of the extracted cuticular fragments in reflected and transmitted light (Figs. 11A, B) confirmed the lack of dorsal setation and the presence of polygonal reticulation of the cuticle, similar to that of P. minaevi (Fig. 1H). Imaging with SEM revealed the presence of longitudinal grooves on the external surface (Figs.11C, E), which can be the result of fossilization. In addition, the inner layer of the cuticle contained thick mesh (Figs. 11 I, J). This mesh, however, cannot be responsible for the polygonal reticulation visible in transmitted light, as these structures are of different scale (compare the same fragment imaged in Figs. 11G–J), but it still can be resolved in transmitted light at higher magnification. Rotating one of the fragments and imaging its internal surface (relative to the mite) revealed arrays of regular pits with probable deeper orifices at their bottoms (Figs. 11D, F) similar in size to the pattern of the cuticle seen in transmitted light (compare Figs. 11B, D).