Lionepha Casey, 1918: 18

Lionepha Casey, 1918: 18 View in CoL .

Type species: Bembidium erasum LeConte, 1859 , by original designation.

Diagnosis: Although DNA sequence data shows Lionepha to be clearly separate from the large genus Bembidion ( Maddison, 2012; Maddison et al., 2019), their morphological distinctiveness is not as evident. The arrangement of internal sac sclerites of male genitalia is perhaps the best defining character of the group, but we do not understand homologies of these structures to other bembidiines in sufficient detail to propose synapomorphies of either Lionepha or Bembidion . Female genitalic evolution is even more poorly understood in general, but Lionepha has a bursal characteristic that is likely derived. The dorsal surface of the bursa of female Lionepha has a region that is darker than the surrounding membrane, and is covered with a mat of microtrichia so dense that it is brown ( Fig.9). The microtrichia ( Fig. 10) are arranged in short rows, point posteriorly and appear to be on the inside of the bursa. This brown region was called the ‘dorsal sclerite’ by Erwin & Kavanaugh (1981), but we call it the ‘dorsal microtrichial patch’. We do not know of any other bembidiines with a similar structure, although the carabid genus Dyscolus ( Platynini ) has a dense microtrichial patch encircling the bursa ( Moret, 1989). Within trechites, the dorsal microtrichial patch appears to be an autapomorphy of Lionepha . As such, it does not help to place the lineage. In external characters, Lionepha are no more distinctive than many subgenera of Bembidion .

Nonetheless, adult Lionepha can in general be recognized by the following suite of characters: they are moderate-sized bembidiines (3.3 to 6.0 mm) with unspotted, brown to black bodies. In body form, the smaller members are reminiscent of Phyla (currently considered a subgenus of Bembidion ). Head with frontal furrows parallel, not deep and not prolonged onto clypeus; antennae short and thick. Mentum with full, more or less triangular epilobes and triangular or subtriangular mentum tooth. Pronotum with deep basolateral foveae, bounded externally by a strong, forward-converging carina. Lateral margin of elytra not prolonged inside shoulder; recurrent groove short, preapical seta (Ed7B) free; discal setae of elytra confluent with third stria; only the first elytral stria reaches elytral apex, striae 6–8 absent or nearly so. Metasternal process completely bordered. Hind wings in most species full, but dimorphic in L. erasa and L. casta . Female bursa with a dorsal microtrichial patch consisting of a dense, brown mat of microtrichia. Twelve pairs of autosomes, in contrast to the 11 pairs of the vast majority of Bembidion ; males lack a Y chromosome (and thus Lionepha have an XO/ XX sex chromosome system).

Larvae of Lionepha are not distinguishable from larvae of Bembidion . We have studied two first-instar larvae of Lionepha casta (obtained ex ovo from a culture of adults), as well as a single fieldcaught first-instar larva of Lionepha erasa (this is specimen DNA2586; see Figs 5, 6). Lionepha larvae have setae FR4 and FR5 closely approximate on the head, a synapomorphy of Amerizus , Asaphidion and Bembidion ( Grebennikov & Maddison, 2005; Maddison, 2012), as well as all other features of Bembidion larvae documented by Grebennikov & Maddison (2005).

Lionepha is composed of two clades ( Fig. 8): the L. erasa group, containing the smaller Lionepha , and the L. osculans group, containing the four species with larger adults. These two groups have distinct male genitalia, with the L. osculans group having a broad apex, and the L. erasa group having a uniform pattern of internal sac sclerites ( Figs 11–13).

The following species of Lionepha are now known (the novel taxa are described below):