Cycadophila (s. str.) mumia, Alekseev & Bukejs, 2017

Alekseev, Vitalii I. & Bukejs, Andris, 2017, First fossil representatives of Pharaxonothinae Crowson (Coleoptera: Erotylidae): indirect evidence for cycads existence in Baltic amber forest, Zootaxa 4337 (3), pp. 413-422 : 415-418

Cycadophila (s. str.) mumia sp. nov.

( Figs 1–9 )

Type material. Holotype: No. 280-4 [CCHH], adult, sex unknown. Beetle inclusion in a small amber piece embedded in a block of GTS-polyester resin with dimensions 13 × 7.5 × 6 mm. Syninclusion: one specimen of Sciaridae ( Diptera : Nematocera).

Paratype: No. 0 43 [CAB], adult, sex unknown. Complete beetle included in a small, yellow subquadratic amber piece with approximate dimensions 19 × 18 × 5 mm and weight 1.2 g. Mouthparts and ventral side of the specimen obscured by “milky” opacity. Syninclusions: one stellate trichome, and few small gas vesicles.

Type strata. Baltic amber, mid-Eocene to Upper Eocene.

Type locality. Yantarny settlement (formerly Palmnicken ), Sambian (Samland) Peninsula, the Kaliningrad region, Russia.

Etymology. The specific epithet is derived from the medieval Latin, meaning “mummy, an embalmed corpse”. It is a noun in apposition.

Differential diagnosis. Cycadophila mumia sp. nov. differs from extant species of the subgenus in the following combination of characters: submental-gular suture with deep depression (similar to Cycadophila abyssa Skelley, Xu & Tang, 2017 and C. cyclochasma Skelley, Xu & Tang, 2017 ); comparatively smaller body length (about 3.8 mm); strongly transverse pronotum (length to width ratio 0.6); pronotal anterior margin curved, sinuate behind eye; supraocular stria long, reaching anterior inner angle of eye; body unicolorous ochraceous or dark brown without dark maculation along elytral suture; posterior portion of hypomera strigose.

Description. Holotype. Body elongate, oval, weakly convex, apparently glabrous dorsally; unicolorous ochraceous. Body length 3.75 mm, maximum body width 1.5 mm; pronotal length 0.78 mm, maximum pronotal width 1.3 mm; elytral length 2.8 mm.

Head. Eyes prominent, coarsely faceted (10–11 facets in longitudinal axis), wide ventrally in relation to dorsal width; interfacetal setae not apparent. Dorsal interocular distance/ head width ratio 0.83; ventral interocular distance/ head width ratio 0.58. Clypeus convex, rounded apically. Supraocular stria present, long (reaching anterior inner angle of eye). Frons slightly convex. Vertex and transverse occipital ridge (vertexal line) not discernible in holotype because posterior portion of head retracted into pronotum. Punctation on frons rather dense (distance between punctures equal to 1.0–1.5× diameter of one puncture), becoming fine and sparse toward clypeus; clypeus punctures become finer and sparser toward apical margin where they disappear. Terminal maxillary and labial palpomeres almost equal in shape and size, elongate, mucronate, as wide as and no less than twice longer than penultimate palpomeres. Mentum subtriangular, rounded apically, impressed, with two symmetrical lateral pockets. Submentum distinctly punctate, separated from gula by transverse, dumbbell-shaped, deep impression. Antennae 11-segmented with 3-segmented club oval in cross section; relatively short and robust, extending to base of pronotum, bearing small setiferous punctures. Scape and pedicel cylindrical; antennomeres 3– 4 almost as long as wide; antennomeres 5–8 slightly conical; antennomeres 9–10 transverse; antennomere 11 rounded. Relative length ratios of antennomeres 1–11 equal to 9:8:6:6:5:5:5:5:8:9:8.

Thorax. Pronotum evenly convex, transverse, 1.7× as wide as long, widest in the middle with narrow longitudinal sulcus posterolaterally, located at half distance between midline and lateral margin, sulci as long as one-fourth of pronotal length. Lateral margins slightly arcuate, widely bordered; anterior margin slightly arcuate, narrowly bordered; posterior margin bisinuate, narrowly bordered. Anterior angles weakly developed, obtusely rounded; posterior angles almost rectangular. Pronotal punctation fine and sparse, distance between punctures equal to 2.0–5.0× diameter of one puncture.

Elytra elongate-oval, about 1.8× as long as wide combined, 3.6× as long as pronotum; without marginal line at base (with only weak rudiment in humeral area); with impressed sutural impunctate stria in apical one-third of elytral length. Elytral punctures fine (about as large as pronotal punctures) and dense, forming non-impressed striae on disc and confused laterally. Scutellary striole shortened, extending to one-fourth of elytral length. Interstriae flat, with row of extremely fine secondary punctures. Epipleura well developed, extending to elytral apex. Scutellar shield distinctly transverse, pentagonal with rounded angles, twice wider than long; scutellar surface not visible because of structure of amber. Hind wings not visible.

Prosternum and anterior portion of hypomeron punctured, posterior portion of hypomeron strigose. Procoxal process expanded beyond procoxal area. Procoxal cavities open externally. Mesoventrite sparsely punctured.

Articulation between meso- and metaventrite monocondylic. Mesocoxal cavities open. Mesepimeron and mesepisternum with dense and coarse punctures. Metaventrite slightly convex, with small, sparse punctures, distance between punctures equal to 2.0–4.0× diameter of one puncture. Mesocoxal lines absent. Metaventrite with distinct transverse row of small punctures (about 15 punctures) along metacoxal cavities; and with central longitudinal fine line (discrimen), apparent in basal half. Metepisternal ctenidium absent.

Legs short and robust. All coxae distinctly separated, pro- and mesocoxae semiglobular, metacoxae transverse, elongate-oval. Coxae, femora and tibiae finely and densely punctate. Femora fairly robust, compressed laterally, with slightly concave, glabrous surface ventrally to receive tibiae. Tibiae gradually dilated to apex, with apical fringe of short and narrow spinules. Tarsi pentamerous. Tarsomeres 1–3 not lobed beneath, pubescent ventrally with long, fine, dense, distally directed setae. Tarsomeres 1–4 cylindrical; tarsomere 4 slightly shorter than tarsomere 3; onychium about as long as tarsomeres 3–4 combined. Onychia paired, simple.

Abdomen. With five visible, similarly articulated ventrites; covered with fine setigerous punctures, distance between punctures 1.5–3.0× diameter of one puncture. Ventrite 1 without subcoxal lines. Intercoxal process of abdominal ventrite 1 narrowly rounded. Relative length (medially, including intercoxal process) ratios of ventrites 1–5 equal to 30:17:17:15:20.

Paratype. Body length 3.6 mm, dark brown. Head with narrow ridge located posteriorly to eye (its medial portion hidden under anterior margin of pronotum); this character is interpreted by us as the lateral portions of a transverse occipital ridge (vertexal suture). Scutellar shield densely covered with small punctures, protibiae more distinctly dilated apically than in holotype; otherwise similar in all visible morphological characters to holotype.

Figures

FIGURES 1 – 3. Cycadophila mumia sp. nov., holotype, habitus: 1 — dorsal view; 2 — ventral view; 3 — lateral view. Scale bar = 1 mm.

FIGURES 4 – 8. Cycadophila mumia sp. nov.: 4 — habitus, dorso-lateral view, paratype; 5 — details of forebody, ventral view, holotype; 6 — head and pronotum, dorso-lateral view, paratype; 7 — antenna, paratype; 8 — protibia and tarsus, paratype. Not reproduced to the same scale.

FIGURE 9. Cycadophila mumia sp. nov., reconstruction of habitus, dorsal view. Scale bar = 1 mm.