Cephennomicrus giganteus, Jałoszyński, Paweł & Perkovsky, Evgeny, 2016

Jałoszyński, Paweł & Perkovsky, Evgeny, 2016, Diversity of Scydmaeninae (Coleoptera: Staphylinidae) in Upper Eocene Rovno amber, Zootaxa 4157 (1), pp. 1-85 : 23-24

† Cephennomicrus giganteus sp. n.

( Figs 5 , 71–74 )

Type material. Holotype: Late Eocene of Europe , Rovno amber: sex unknown; inclusion in elongate, irregular prism of amber 21.5 mm long ( Fig. 5 ), collection number K-6011 ( SIZK).

Diagnosis. This is an unusually large adult, BL 1.55 mm, body slender (EI 1.48), densely covered with fine setae; pronotum with two pairs of antebasal pits connected by transverse groove.

Description. Body ( Figs 71–74 ) elongate and strongly convex, light brown with slightly lighter appendages; BL 1.55 mm.

Head ( Figs 71–74 ) broadest at eyes, HL 0.18 mm, HW about 0.28 mm; head structures poorly visible, compound eyes large, slightly bean-shaped and strongly convex, finely faceted. Antennae ( Figs 71–74 ) about half BL, AnL about 0.75 mm, scape and pedicel strongly elongate, antennomeres III–VIII elongate, IX–X distinctly transverse, XI about as long as IX–X combined, slightly broader than X, less than twice as long as broad and slightly asymmetrical.

Pronotum ( Figs 71, 73 ) subrectangular with rounded anterior margin; PL 0.38 mm, PW 0.45 mm; pronotal disc broadest near anterior third, sides rounded in anterior half and slightly concave near posterior third; posterior pronotal corners distinct; posterior margin arcuate; base with two pairs of small and shallow but distinct antebasal pits ( Fig. 73 ; abp) connected by narrow transverse antebasal groove ( Fig. 73 ; abg). Punctures on pronotal disc fine but distinct, separated by spaces subequal to diameters of punctures; setae short, moderately dense, nearly recumbent ( Figs 71, 73 ).

Elytra ( Figs 71–74 ) elongate oval, strongly convex, EL 1.00 mm, EW 0.68 mm, EI 1.48; punctures slightly larger than those on pronotal disc; setae similar to those on pronotum ( Figs 71, 73 ).

Legs ( Figs 72, 74 ) moderately long, slender, unmodified; all tibiae straight or weakly curved.

Etymology. The name giganteus refers to the exceptionally large body of this new species.

Remarks. The cephenniine genus Cephennomicrus can easily be identified on the basis of characters summarized in Jałoszyński (2011a): the maxillary palpomere IV very short and broad, button-like; the pronotum typically with four antebasal pits and often with a transverse groove; each elytron with two small and asetose basal foveae; the prosternal process narrow, subtriangular and weakly elevated, but distinctly separating procoxae; and the mesoventral intercoxal process moderately broad and not elevated. All these characters can be seen in the studied inclusion, and also the general body form is typical of Cephennomicrus .

Cephennomicrus currently comprises 74 extant species distributed in the Afrotropical ( South Africa, Congo, Tanzania, Madagascar, Mauritius, Seychelles, Reunion Island and Grand Comore Island) and Oriental regions ( Sri Lanka, Thailand, Taiwan, subtropical China and Japan, West Malaysia and Sumatra), extending through the Philippines and Papua New Guinea to Australia (including Lord Howe Island), New Caledonia, Fiji and Samoa ( Jałoszyński 2011a, 2015e). Many undescribed species were seen by the first author from various parts of East and South Asia, especially from the Sunda Islands and several from the Himalayas; also in Australia Cephennomicrus is more speciose than recorded so far, and the poorly studied fauna of Madagascar is exceptionally rich in undescribed species of this interesting genus (Jałoszyński, unpublished obs.). A possibly broader distribution in other parts of Africa, Melanesia, Micronesia and Polynesia was also suggested ( Jałoszyński 2011a). This is, therefore, a large and taxonomically challenging genus, comprising many species so similar one to another that in some cases only the male genitalia can be used for identification (e.g., Jałoszyński 2009a). However, in contrast to other small-bodied Cephenniini , Cephennomicrus shows a relatively large diversity of body shapes, sculpture, vestiture of setae and male secondary sexual characters. This allows for defining species on the basis of external characters, especially when they show conspicuous features. As most Cephennomicrus adults do not reach 1 mm in length, a large body over 1.5 mm is remarkable enough to facilitate species identification. Cephennomicrus giganteus is the largest of all hitherto described species of this genus. The 74 extant species have the body length ranging from 0.48 to 1.30 mm; 30 of them do not reach 1 mm, and only four reach or exceed 1.2 mm. None of them is as large as C. giganteus , which measures 1.55 mm, and this feature alone can be used to distinguish this remarkable extinct species from its extant congeners.

Figures

FIGURES 1 – 20. Specimens of Rovno amber with inclusions of Scydmaeninae. K- 27418, Rovnoleptochromus ableptonoides sp. n. (1); K- 243, Vertheia quadrisetosa sp. n. (2); UA- 442, Vertheia sp. 1 (3); K- 800, Cephennodes sp. 1 (4); K- 6011, Cephennomicrus giganteus sp. n. (5); K- 8289, Cephennomicrus sp. 1 (6); K- 7010, Cephennomicrus sp. 2 (7); K- 27565, Cephennomicrus sp. 3 (8); K- 8912, Cephennomicrus sp. 4 (9); DU- 32, Cephennomicrus sp. 5 (10); K- 5770, Glaesoconnus unicus sp. n. (11); K- 9579, Rovnoscydmus frontalis sp. n. (12); K- 347, Rovnoscydmus microscopicus sp. n. (13); K- 25702, Rovnoscydmus sp. specimen 1 (14); K- 26348, Rovnoscydmus sp. specimen 2 (15); UA- 1556, Rovnoscydmus sp. specimen 3 (16); K- 8970, Rovnoscydmus sp. specimen 4 (17); K- 8968, Rovnoscydmus sp. specimen 5 (18); K- 7350, Rovnoscydmus sp. specimen 6 (19); K- 3037, Rovnoscydmus sp. specimen 7 (20).

FIGURES 71 – 74. Holotype of Cephennomicrus giganteus sp. n. (K- 6011). Habitus in dorsolateral (71, 73) and lateral (72, 74) view. Abbreviations: abg, antebasal groove; abp, antebasal pit; bef, basal elytral foveae; bst, basisternal part of prosternum; hy, hypomeron,; hyr, hypomeral ridge; lpc, lateral pronotal carina; mcp, mesocoxal projection; msvp, mesoventral intercoxal process; mtvp, metaventral intercoxal process; mxp 2 – 3, maxillary palpomere II – III; pg, pygidium; psp, prosternal process; st 3 – 8, abdominal sternite III – VIII; v 3, metaventrite.