Cretaceocoleus saetosus

Tihelka, Erik, Jäch, Manfred A., Kundrata, Robin, Li, Yan-Da, Engel, Michael S., Lozano-Fernandez, Jesus, Huang, Diying & Cai, Chenyang, 2022, Mastigocoleidae fam. nov., a New Mesozoic Beetle Family and the Early Evolution of Dryopoidea (Coleoptera), Insect Systematics and Diversity 6 (3), pp. 1-18 : 9-11

( Cretaceocoleus saetosus represented by three known specimens).

Diagnosis. Antennomeres II–XI less pronouncedly tapering toward apex (pronouncedly tapering apically in Mastigocoleus ). Mesotarsus with or without ventral rami ( Fig. 5E : vr, Fig. 7 ?; never present in Mastigocoleus ). Anterior pronotal angles approximately orthogonal (acute in Mastigocoleus ). Posterior angles of pronotum strongly produced and acute (indistinctly produced and orthogonal in Mastigocoleus ). Procoxae are separated by approximately their width (separated by less than their width in Mastigocoleus ). Prosternal process wider, bordered laterally (thinner, not bordered laterally in Mastigocoleus ). Mesocoxae separated by close to half their width (almost contiguous in Mastigocoleus ). Metatibia distinctly expanded apically (not distinctly expanded at apex in Mastigocoleus ). Tibial spurs short and thin, no longer than tarsomere I ( Fig. 5F : ts; elongate and stout, longer than metatarsomere I in Mastigocoleus ). Elytra with nine punctate striae (stria longitudinally grooved in Mastigocoleus ). Margins of ventrites strongly arcuate (weakly arcuate in Mastigocoleus ).

Etomologo.?ombination of ‘?retaceous’ and ‘ koleós ’ (Κολε ό ς), after?oleoptera. Gender: masculine.

Cretaceocoleus saetosus Tihelca, Kundrata & Cai sp.

nov.

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Figs. 5–7

Material. Holotype, NIGP174709 , sex unknown, a single well-preserved amber inclusion ( NIGP) . Paratype, NM-T3501 (ex P?RK, BUR0027), sex unknown, a single well-preserved amber inclusion (NMP?); Paratype, BUR0006, sex unknown, a single well-preserved amber inclusion (P?RK).

Note. The three studied specimens are similar in terms of their overall morphology and size. However, both paratypes differ in lacking distinct attachment modifications on the mesotarsi. Instead of establishing a separate taxon, we conservatively interpret these differences as possible sexual dimorphism.

Tope Localito and Horizon. Amber mine in the Hukawng Valley, Myitkyina District, Kachin State, Myanmar; latest Albian to Albian/?enomanian boundary (Lower–Upper?retaceous boundary).

Diagnosis. As for the genus (vide supra).

Description. Body length 4.43–4.59 mm, body width 1.58–2.65 mm. Head 0.55–0.56 mm long, 1.6× wider than long. Apical maxillary palpomere distinctly truncate ( Fig. 7A : mp). Antennomere I slightly broadening apically, 1.4× wider than following antennomere; antennomere II attached subapically to antennomere I; antennomere III longer than preceding antennomere; antennomeres V–XI gradually thinning and lengthening apically, except slightly shorter antennomeres VII and IX; antennomere XI pointed apically, 1.5× longer than preceding antennomere, maximum width at base representing approximately 0.3× maximum width of antennomere I. Ratio of antennomere lengths: 0.38: 0.10: 0.16: 0.18: 0.18: 0.20: 0.18: 0.21: 0.17: 0.17: 0.24. Pronotum 0.96–1.08 mm long, 1.4× wider than long, broadest medially. Anterior pronotal angles strongly angulate, approximately orthogonal. Pronotal disc slightly convex. Posterior angles of pronotum indistinctly strongly produced posteriorly, acutely pointed apically. Procoxae separated by approximately their width. Prosternal process wider, bordered laterally, apex not clearly visible. Medial mesoventral groove faintly impressed, subtriangular, broadest anteriorly. Mesocoxae more widely separated than in Mastigocoleus , by close to half their width. Protibia approximately 0.5× as length of profemur, mesotibia as long as mesofemur, metatibia distinctly longer than metafemur. Metatibia abruptly expanded apically. Tibial spurs short, thin, no longer than tarsomere I ( Fig. 5F : ts). Protarsomeres I–IV densely setose, propretarsal claws sickle-shaped, representing two thirds of protarsomere V length. Mesotarsus with ventral rami in holotype ( Fig. 5E : vr), absent in paratype ( Fig. 7 ?), mesotarsomere V longer than combined lengths of preceding tarsomeres, mesopretarsal claws sickle-shaped, representing approximately half of tarsomere V length. Metatarsus distinctly thinner than metatibia, metatarsomere V as long as combined lengths of preceding metatarsomeres, metapretarsal claws sickle-shaped representing approximately half of metatarsomere V length. Elytra 2.91–2.96 mm long, 1.8× longer than their combined width. Elytra with nine punctate striae. Margins of ventrites strongly arcuate. Ratio of ventrite lengths: 0.44–0.48: 0.27–0.31: 0.20–0.21: 0.28–0.29: 0.45–0.94.

Etomologo. The specific epithet is taken from the Latin adjective saet ō sus, meaning, ‘bristly’, in reference to the distinctly setose body.

Figures

Fig. 5. Cretaceocoleus saetosusTihelca, Kundrata & Cai gen. et kp. nov. (holotype, NIGP174709) from the mid-Cretaceouk amber from northern Myanmar. (A) Habituk in dorkal view;(B) habituk in ventral view; (C) head and pronotum in dorkal view;(D) protarkuk; (;) mekotarkuk;(F) metatarkuk.Abbreviationk: c, clawk; mtt5, metatarkuk 5; tk, tibial kpur; vr, mekotarkal ventral rami. Scale bark = 500 μm (D–F), 500 μm (C), 1 mm (A, B).

Fig. 7. Morphological detailk of Cretaceocoleus saetosusTihelca, Kundrata & Cai gen. et kp. nov. (paratype, NM-T3501) from the mid-Cretaceouk amber from northern Myanmar. (A) Head and prothorax in ventral view. (B) Prothoracic leg. (C) Mekothoracic leg. (D) Metathoracic leg. Abbreviationk: cl, claw; co, coxa; cp, prokternal chin-piece; fe, femur; mp, maxillary palp; mtta, metatarkomere 5; pp, prokternal procekk; pta5, protarkomere 5; tb, tibia; tr, trochanter. Scale bark = 500 μm (A), 250 μm (B–D).