Carcinops donelaitisi, Alekseev, 2016

Alekseev, Vitalii I., 2016, Description of two clown beetles (Coleoptera: Staphyliniformia: Hydrophiloidea: Histeridae) from Baltic amber (Cenozoic, Paleogene, Eocene), Baltic Journal of Coleopterology 16 (1), pp. 27-35 : 27-35

Carcinops donelaitisi sp. nov.

( Figs. 1-3 )

Material examined. Holotype: Nr AWI-098 [ CVIA]. The beetle inclusion is preserved in a polished piece of transparent amber with an orange shade without any further fixation. The amber piece is oval, with maximum length 14 mm and maximum width 5 mm. The beetle inclusion is slightly damaged: the elytra are slightly deformed and dorsal surface is not clearly visible, because of the hypothesized thermal processing of the amber piece in an autoclave. The right antennal club is lost. Syninclusions: legs and abdominal apex of two Diptera, three Collembola specimens, numerous small pieces of organic material.

Type strata. Baltic Amber, Eocene.

Type locality. Yantarny settlement [Palmnicken], Sambian [Samland] peninsula, Kaliningrad region, Russia .

Description. Total length (measured from anterior margin of pronotum to posterior margin of elytra) 1.5 mm, maximal body width 0.8 mm. Body elongate, parallel-sided, slightly convex, glossy, smooth, without visible punctures (except stria on elytra, femora ventrally, propygidium and pygidium). Color black throughout.

Head. Transverse, narrower than prothorax. Eyes pr esen t, oblong, later al. An ten n ae geniculate. Scape (1. antennomere) long, three times longer as pedicel (2 nd antennomere); funicle consists of pedicel and 5 visible segments; pedicel slightly longer than 2 following antennomeres combined; the antennal club rounded, without visible segmentation.

Thorax. Pronotum transverse (length/width ratio 0.67), parallel-sided, with clearly defined marginal striae; anterior margin almost straight, weakly emarginate behind head. Prosternal lobe present, projected and truncate anteriorly, impressed along anterior margin by marginal stria. Antennal cavities situated in front of procoxa forming longitudinal deep furrows. Prosternal keel with short separated carinal stria medially. Intercoxal process almost parallel-sided, apically rounded. Mesoventrite short, transverse, about 1.5 times wider than long. Scutellum distinct, triangular. Mesocoxal cavities broadly separated, distance 2.5 times wider than between procoxae and slightly narrower than between metacoxae. Mesometasternal suture arcuate. Lateral metasternal sutures present. Metaventrite with longitudinal suture.

Wings. Elytra glabrous, shining, truncate, almost parallel, with punctures in striae only; two external striae distinct in full length and comparatively deep; 3 inner striae at the disc shallow and clearly visible on specimen in apical part of elytron only and with distance between punctures larger than each puncture diameter. Hind wings not apparent.

Legs. Femora flattened, with sparse and large punctures ventrally. Pro- and mesotibiae dilated, rounded in outline, with small teeth on the pro- and mesotabiae. Protibia with shallow tarsal groove on the dorsal surface and with four weak teeth on outer margin. Protibial spur long, curved. Tarsal formula 5-5-5. All tarsomeres longer than wide, the ultimate tarsomere the longest. Claws simple, acute, symmetrical.

Abdomen. Two last visible tergites are exposed and not covered by the elytra. Propygidium almost twice shorter than pygidium. Pygidium and propygidium with large and sparse punctures as on femora. Pygidium convex, apically rounded. First visible abdominal sternite the longest, almost equal to all others combined. Lateral stria of first abdominal sternite obscured by position of legs.

Remark. The carinal striae on prosternal keel are poorly discernible in the specimen and apparently form two symmetrical separate lines in medial part of keel only (e.g. are not joined apically).

Differential diagnosis. The specimen AWI-098 can be referred to the subfamily Dendrophilinae Reitter, 1909 due to the longitudinal antennal cavities and the presence of a prosternal lobe. The new species is assigned to the tribe Paromalini Reitter, 1909 , which is characterized by more or less dorsoventrally flattened body, expanded protibiae, presence of a narrow prosternal lobe, and broad trapezoidal epistoma ( Kryzhanovskij & Reichardt 1976; Ôhara & Paik 1998). Two external characters (well-developed frontal stria, transverse labrum) diagnostic of tribal placement ( Zhang & Zhou 2007) are not clearly visible on specimen. The specimen AWI-098 was assigned to the genus Carcinops Marseul based on the following characters: (1) elytral disk with distinct dorsal striae; (2) prosternal keel with carinal stria; (3) elongate tarsomeres I-IV; (4) triangular distinct scutellum; and (5) metaventrite with longitudinal suture but without second lateral striae.

Carcinops donelaitisi sp. nov. differs from majority of the extant congeneric species by the non-oval body form and is similar to the Nearctic C. tejonicus (Horn, 1873) in that character. The new species from Baltic amber can be easily distinguished from C. tejonicus by the almost indistinct pronotal and interstrial elytral punctuation; by the shortened carinal striae of prosternal keel with posterior ends not united with each other; and by the form and distance between protibial teeth.

Derivatio nominis: The epithet of this new species is devoted to the poet Kristijonas Donelaitis [(1714 (Lasdinehlen) 1780 (Tollmingkehmen)], who lived in Lithuania Minor [Kleinlitauen, present-day eastern parts of Kaliningrad region] and wrote the first classical poem in Lithuanian language, “Metai” (“The seasons”), which became one of the principal works of Lithuanian poetry and a classical work of Lithuanian literature.

Figures

Figures 1-2. Carcinops donelaitisi sp. nov. Holotype; No. AWI-098 [CVIA]. Habitus: 1 - Dorsal view; 2 - Ventro-lateral view.

Figure 3. Carcinops donelaitisi sp. nov Habitus dorsally, reconstruction