Balticranocapsus Kim, Taszakowski & Jung, 2023

Kim, Junggon, Taszakowski, Artur & Jung, Sunghoon, 2023, A new genus and two new species of fossil deraeocorine plant bugs (Hemiptera: Heteroptera: Miridae) from Eocene Baltic amber, Zootaxa 5382 (1), pp. 170-178 : 171-173

Genus Balticranocapsus Kim, Taszakowski & Jung , gen. nov.

( Fig. 1 )

Type species: Balticranocapsus aleksanderi sp. nov.; by present designation.

Diagnosis: Differs from the other genera in Deraeocorini by the following combination of characters: body elongate oval ( Fig. 1A ); head prognathous; second antennomere clavate, thicker than third antennomere, length subequal to combined lengths of third and fourth antennomeres; third antennomere shorter than fourth antennomere ( Figs. 1B, C, E ); pronotal collar subequal to first antennomere diameter; callosite strongly punctate; scutellum large and strongly tumid, mesoscutum clearly broad and punctate ( Fig. 1D ); legs somewhat thickened; third tarsomere longest, shorter than combination of first and second tarsomeres ( Fig. 1F ).

Description: Body elongate oval, length 4.23 mm. Surface and vestiture. Body glossy, mostly punctate, densely covered with short erected pubescence; head impunctate, covered with short pubescence ( Figs. 1A, D ); callosite strongly punctate, covered with dense pubescence; mesoscutum clearly punctate ( Fig. 1D ). Structure. Head: prognathous, length shorter than width, shorter than pronotal midline, longer than first antennomere length; vertex wide, wider than width of a single compound eye; antennae generally linear, shorter than body length; first antennomere shortest, subequal to head length, longer than vertex width; second antennomere slightly clavate, subequal to combined length of head and pronotum, subequal to combined length of third and fourth antennomeres, clearly thicker than third, fourth antennomere; third antennomere shorter than fourth antennomere ( Fig. 1E ); Thorax: pronotum trapezoidal, anterior width shorter than head width; pronotal midline length longer than 1/2 of basal width, clearly longer than scutellar midline length; scutellum large, tumid laterally; mesoscutum broadly developed; scutellar midline length subequal to scutellar width and commissure length; lateral margin of hemelytra rounded; embolial area narrow; cuneus equilateral triangular, inner margin slightly sinuate; legs somewhat short and thickened; hindleg length subequal to body length; tarsus subequal to 1/3 tibia; third tarsomere longest, shorter than combined length of first and second tarsomeres. Abdomen: elongate, extending to apex of cuneus.

Etymology: The name was created after a combination of the prefix ‘Baltic’, referring to the type locality of the fossil, and the related genus ‘ Cranocapsus Wagner, 1954 ’, due to its similarity; gender masculine.

Remarks: The placement of this fossil as a mirid bug is supported by the two closed cells on the membrane and a distinct cuneus. The femoral trichobothria could not be seen. The assignment of the fossil as a deraeocorine member is supported by having the rounded pronotal collar, punctate dorsum, the structure of antennae and the pretarsal claw with the large basal tooth ( Cassis & Schuh 2012; Schuh & Weirauch 2020). Although it is hypothesized that the Deraeocorini are not monophyletic, being nested with the surinamelline taxa ( Kim et al. 2023), it is reasonable to place the new fossil Balticranocapsus gen. nov. in the tribe Deraeocorini by the characters provided within the diagnosis section, as the current deraeocorine tribes have their own characteristics (e.g., Hyaliodini : having hyaline embolium, and Saturniomirini : having a serrate lateral margin of scutellum). In Deraeocorini , Balticranocapsus gen. nov. is distinguished from the largest genus Deraeocoris Kirschbaum, 1856 s. lat. by the combination of the following characters: second antennomere subequal to the combination length of third and fourth antennomeres; third antennomere shorter than fourth antennomere; punctate callosite; largely developed mesoscutum; strongly tumid scutellum (although the tumid scutellum is found in several Deraeocoris species); the shortest first tarsomere (vs not the shortest first tarsomere); and the longest third tarsomere, shorter than the combined lengths of first and second tarsomeres. This new genus is also distinguished from the exemplar of Deraeocorini , Alloeotomus Fieber, 1858 by the proportion of antennomeres, ratio of second antennomere to combined third and fourth antennomeres; punctate callosite (vs impunctate callosite); tumid scutellum; and short first tarsomere (vs longest first tarsomere). In addition, Balticranocapsus gen. nov. is distinguished from one of the largest genera, Eustictus Reuter, 1909 which was recently transferred to Deraeocorini ( Kim et al. 2023) by the prognathous head (vs hypognathous head); first antennomere subequal to head length (vs longer first antennomere than head length); structure of antennae (vs second antennomere as thick as third antennomere); third antennomere shorter than fourth (vs third antennomere longer than fourth); moderate-length hindleg (vs very long hind leg); and the proportion of tarsomeres.

Among the genera in Deraeocorini , this new fossil is similar to the genus Cranocapsus based on the head structure (ratio of compound eye width and vertex width); pronotum (callosite with punctuations); scutellum (tumid scutellum, broad mesoscutum and ratio of scutellar midline length and commissure length); legs (somewhat thickened and short) and tarsus structure. In particular, the proportion of tarsomeres and the claw structure are almost the same as in the members of the genus Cranocapsus (see the original description of Cranocapsus in Wagner 1954), which is the only case sharing the same tarsus structure within Deraeocorini . As for the antennal structure, Wagner (1974) illustrated the antennae (third antennomere shorter than the fourth) of Cranocapsus pictus Wagner, 1967 , although the third and fourth antennomeres are shorter than the second antennomere. Despite the fact that other Cranocapsus s. lat. species have different proportions of antennal segment lengths (e.g., C. acuticeps Linnavuori, 1973 ), this genus is most similar to Balticranocapsus gen. nov. within Deraeocorini . Balticranocapsus gen. nov. is distinguished from Cranocapsus by having its dorsum mostly covered with dense pubescence (vs dorsum covered with sparse pubescence) and punctate mesoscutum (vs impunctate mesoscutum).

The new genus Balticranocapsus gen. nov. shows clear differences with the recently described fossil deraeocorine species from Miocene Dominican amber, Amberderaeous gigophthalmus and Electroderaeous crassicornis by having a prognathous head (vs hypognathous head); small compound eyes (vs large compound eyes relative to vertex width); second antennomere thicker than third (vs second antennomere as thick as third); and punctate callosite (vs impunctate callosite).

Figures

FIGURE 1. Balticranocapsus aleksanderi sp. nov., holotype (CNUHHMF006). A, dorsal habitus. B, C, lateral habitus. D, head, pronotum and scutellum. E, antennae. F, hind tarsus. G, claw. Scale bars: 1 mm.