Calisius balticus Usinger, 1941

Marchal, Lorene, Guilbert, Eric, Brisac, Patrick & Nel, Andre, 2011, A new record and a new species of Aradidae fossils (Hemiptera: Heteroptera), Zootaxa 2832, pp. 56-62 : 59-61

Calisius balticus Usinger, 1941 , new record

Figs. 2a –c

Description of new specimen. Male. Body elongate, 2.7 mm long.

Head broader than long (width/length, 16/13); clypeus pyramidal, very large and long, proportion length of clypeus/length of head, 5/13; genae not produced on either sides of clypeus; rostrum arising well behind apex of clypeus, with its base bordered by buccal plates, short, not reaching posterior margin of head; a row of small tubercle around dorsal base of eye; antenniferous tubercle with one spine; antenna elongate, only slightly shorter than head width; three basal segments elongate, with proportions of antennal segments 2/3/3/5.5; eye prominent, rather large; a series of rather high tubercles on postocular surface.

Pronotum transverse (width of anterior part/width of posterior part/length, 25/18/18), with a strong constriction between its anterior and posterior parts; anterior angle with a small spine; pronotal callosities organized in four subparallel longitudinal lines, rather elevated; scutellum very long and broad, covering main part of abdomen and wings, width/length, 18/34; scutellum without depressions, but with a pronounced median crest and covered with numerous small granules; ventral side of thorax partly destroyed but metapleuron without a large and deep scent gland opening in front of hind coxa.

Abdomen elongate (width/length, 32/42); external border of connexivum without spicules, but with a double row of granules.

Material. MNHN.F.A33749 (PA 12511), mounted in Canada Balsam, Muséum National d'Histoire Naturelle, Paris.

Type strata. Lowermost Eocene, in amber, circa - 53 Myr, Sparnacian, level MP7 of the mammal fauna of Dormaal.

Type locality. Farm Le Quesnoy, Chevrière, region of Creil, Oise department (north of France).

Comments. Following the key to subfamilies of Usinger and Matsuda (1959), this fossil falls in the Calisiinae Stål, 1873 because of the following characters: genae not produced on either sides of the clypeus; clypeus very large; rostrum arising well behind apex of clypeus, with its base bordered by buccal plates; metapleuron without a large and deep scent gland opening in front of hind coxa; scutellum greatly enlarged, covering nearly all but a narrow margin of abdominal disk, with hemelytra completely hidden.

This fossil does not fit in the Cretaceous subfamily Archearadinae Heiss & Grimaldi, 2002 for the same characters ( Heiss & Grimaldi 2002).

This subfamily comprises the six recent genera Calisius Stål, 1860 (also in Baltic amber), Calisiopsis Champion, 1898 (also in Miocene Dominican Republic amber), Aradacanthia Costa, 1864 , Paracalisiopsis Kormilev, 1963, Paracalisius Kormilev, 1974, Heissia Kormilev, 1986, and the fossil genus Allocalisius Heiss, 2002 (Baltic amber) ( Kormilev & Froeschner, 1987; Heiss, 2002a).

This fossil differs from the genera Paracalisius, Paracalisiopsis, Calisiopsis, and Aradacanthia in its longer antenna, nearly as long as head wide across eyes, with the three basal segments not monoliform ( Kormilev 1963: 605, fig. 6, 1974: fig. 1, 1976: fig. 3, 1986: 249–250; Froeschner 1992). It differs from Heissia in its external bor- der of connexivum without spicules, but with a double row of granules, as in Calisius (Kormilev 1986: fig. 2). It differs from Allocalisius in the absence of a ventral row of granules and its narrower clypeus ( Heiss 2002a: figs 1– 3, photo 4).

The fossil record of the genus Calisius comprises five species ( Usinger 1941; Heiss 2000a, 2002a). This fossil differs from Calisius vonholti Heiss, 2000 and Calisius hoffeinsorum Heiss, 2002 in the absence of depressions on scutellum ( Heiss 2000a: fig. 4, 2002a: fig. 4). This fossil is slightly longer than Calisius weitschati Heiss, 2000 (2.7 mm long instead of 2.25 mm), and its granules of connexivum are larger than in this last species. Calisius rietscheli Heiss, 2000 is distinctly larger than this fossil (3.65 mm long). This fossil has nearly the same length, nearly the same head, antennal and thorax proportion as Calisius balticus Usinger, 1941 . Also, it has nearly the same body ornamentation (granules of head, pronotum, scutellum, and abdomen). Therefore, we propose to attribute it to the same species, despite of its greater antiquity (53 Ma old, instead of about 44 Ma for the type material of C. balticus from Baltic amber) ( Wappler 2003).

This fossil is the second case of an insect species present in both the Oise and the Baltic amber, after the Psocoptera: Archipsocidae Archipsocus puber Hagen, 1882 , already known from Baltic amber ( Nel et al. 2005). These are interesting cases of morphological stasis of insects during more than 10 Ma, supporting the possible ‘long’ life for such organisms ( Hörnschemeyer et al. 2010), maybe in relation with stasis of their biotas, as they live under barks or in soil litter.

Figures

FIGURE 2 A. Calisius balticus, habitus from dorsal view. Scale: 1 mm. FIGURE 2 B. Calisius balticus in Oise amber, dorsal view. Scale: 1 mm. FIGURE 2 C. Calisius balticus in Oise amber, ventral view. Scale: 1 mm.