Anapleus punctulatus, Jan & ºimon-Pražák & Yamamoto & Lackner & Fikáček & Prokop & Michael & Caterino, 2024

Simon-Pražák, Jan, Yamamoto, Shûhei, Lackner, Tomáš, Fikáček, Martin, Prokop, Jakub & Caterino, Michael S, 2024, A bonanza of Cretaceous fossils provides insights into the evolution of antennal protection in clown beetles (Coleoptera: Histeridae), Zoological Journal of the Linnean Society (zlae 137) 202 (3), pp. 1-28 : 8-10

Anapleus punctulatus sp. nov.

( Fig. 6 )

Material: Hkamti amber (c. 110 Mya). Amber piece dimensions: 14 × 8 × 1 mm. Amber clear with several insect fragments and air bubbles. Deposited at HUM ( SEHU-0000121214 ) .

Measurements: Head width: 0.2 mm; width between anterior pronotal angles: 0.25 mm; width between posterior pronotal angles: 0.6 mm; pronotal length: 0.31 mm; sutural elytral length: 0.65 mm; elytral width (in pair, across widest point): 0.8 mm.— Body: Rounded widest at humeri, anteriorly narrowed. Dorsal and ventral surface with dense and rugose punctuation. Lateral body margin elevated dorsally. Cuticle black, legs chestnut brown.— Head: Frons and clypeus punctuate (punctures separated by two to three times their diameter). Frontoclypeal area with a round concavity. Frontal and frontoclypeal striae absent. Labrum trapezoidal with several setae. Mandibles robust, with outer surfaces punctate; Head retracted, other mouthparts not observable. Antennal insertions rather broadly open to front; Scape short, slender, only weakly widened to apex; Pedicel slender, mostly hidden; Antennomeres 3–8 simple, rounded. Antennal club round, with distinct annuli and several prominent setae.— Thorax: Pronotum convex medially. Entire pronotal disc covered with dense and rugose punctuation (punctures separated by their diameter). Basal margin rounded, slightly angularly projecting posteriorly. Pronotum bi-margined laterally, strongest lateral carina aligned with marginal elytral carina; outer marginal pronotal stria similarly carinate, narrowing and descending below inner marginal in anterior half, overlapped and invisible from above in the anterior third. Scutellar shield obscured. Elytra with the same punctuation pattern as pronotal disc. Elytral disc slightly convex, with two weakly elevated longitudinal carinae located in medial part. Elytra carinate along the outer margin and truncate posteriorly. Sutural area elevated in posterior third forming a keel. Marginal elytral stria carinate, deeply impressed. Elytral epipleuron with two carinate striae. Prosternal lobe very short and broad with dense punctuation, with incised furrows laterally for passage of the antennal funicle; Prosternal keel broad, similarly punctate to prosternal lobe, with lateral carinae weakly converging anterad, abruptly narrowing at junction with prosternal lobe; basal prosternal margin weakly and broadly emarginate. No striation visible on prosternum. Antennal cavities widely open, located posterolaterally on prosternal sides. Mesoventrite wide, densely and coarsely punctuated. Anterior margin outwardly curved along prosternal margin. Metaventrite with a pair of lateral metaventral striae present in anterior two-thirds, extending laterally to near metepisternum. Postmesocoxal striae curved along mesocoxae. Punctures on metaventrite become sparser and larger posteriorly.— Legs: Profemur wide and flat, with a groove for protibial reception. Protibia curved with a row of short setae along the outer margin. Protibial margins slightly thickened, creating a shallow protibial groove just mediad the outer margin. Protibial spur absent. Mesofemur narrow, mesotibia very slender, with a row of short setae along inner and outer margin. Hind leg identical to middle leg. Tarsi 5-5- 5, with ultimate tarsomere similar in length to the combined tarsomeres 2–4; tarsomeres 2–4 bearing a single pair of apical setae ventrally.— Abdomen: All abdominal ventrites with dense punctuation (but finer than on thoracical ventrites). First ventrite with a pair of parallel lateral striae and a pair of curved postmetacoxal striae. Propygidium and pygidium coarsely and densely punctured.

Taxonomic assignment: We place this species within the tribe Anapleini based on the morphology of the protibia, as defined by Olexa (1982): tarsal groove of protibia formed by marginal thickening, row of setae along the outer margin ( Fig. 6D ). Other characters typical for Anapleini include weakly defined and widely open antennal cavities and two elytral epipleural striae ( Fig. 6B ). This species is furthermore assignable to the genus Anapleus Horn, 1873 with which it shares the simple frontoclypeal area without striae.

Differential diagnosis: Two species of Anapleini have been described from the Kachin amber so far: Anapleus kachinensis Jiang et al., 2022 and Cretanapleus seideli Simon-Pražák and Lackner, 2023. Cretanapleus seideli can be easily distinguished by the presence of a strongly carinate frontal stria, as well as dorsally explanate body margin. Anapleus punctulatus sp. nov. can be differentiated from Anapleus kachinensis by the more rugose and dense body punctuation, by the presence of carinate marginal pronotal and marginal elytral striae ( Fig. 6A ), presence of a distinct lateral metaventral stria ( Fig. 6B ), and the absence of a strong protibial spur ( Fig. 6D ).

Etymology: Named after its coarsely punctate cuticle.

Figures

Figure 6. Anapleus punctulatus sp.nov.. A, dorsal view.B, elytral epipleuron. C, ventral view.D, frontal view.Abbreviations:ees, elytral epipleural striae; lps, lateral pronotal stria; mes, marginal elytral stria; mps, marginal prosternal stria; ms, metaventral stria.