Dilacera Zilberman & Pires-Silva, 2022

Zilberman, Bruno & Pires-Silva, Carlos M., 2022, Dilacera, a new astonishing Amazonian genus of termitophilous rove beetle (Staphylinidae: Aleocharinae: Termitonannini) and updated checklist of the subtribe Termitonannina with their termite hosts, Zootaxa 5194 (1), pp. 122-132 : 123

Dilacera Zilberman & Pires-Silva gen. nov.

Type species: Dilacera exokosmos Zilberman & Pires-Silva sp. nov.

Diagnosis: Head deflexed, slightly wider than long, strongly impressed on the medial region of vertex through the front, with eyes diverging anteriorly, strongly prominent, leaving the impression of the eyes popping out from the head; antenna fusiform, with pedicels not visible; fourth maxillary palpomere rather large and with a broad sensorial pit at apex; lacinia divided into internal and outer lobes; pronotum concave on anterior region and convex posteriorly; metendesternite with apex of arms ending in spoon-like sclerotized regions; legs with first three tarsomeres each bearing a spine on basal part; abdomen mostly sclerotized, with only segment II with significant areas of membrane exposed, flattened, widest at segments IV-VI, segments III-VI with a single and broad transverse paratergite on each side; segment VII with highly modified, semi triangular and big paratergites, which along with the modified sternite VII and spear-head shaped tergite X, turns the abdominal apex acute.

Comparative notes: The genus Dilacera gen. nov. is easily distinguished from any other in Termitonannina , with unique characters along the whole body. The head is strongly impressed, and with the eyes diverging anteriorly, strongly prominent, seemingly popping out from the head, antennomeres with pedicels not visible, along with the lacinia divided into two lobes, each character, individually or combined, turns the head unparalleled within the subtribe. The third maxillary palpomere is pear-shaped instead of the usually longer ones of the other genera, the fourth being large is somewhat distinct, though its enlargement has occurred in other genera such as Nannusa Borgmeier , some Termitonannus Wasmann , and especially Termitocomes Seevers ; however, the broad sensorial pit is seemingly unique for Dilacera gen. nov.

The shape of pronotum in most Termitonannina is wider posteriorly, narrowing through the anterior region, except for Nannusa longicornis Borgmeier, 1959 and slightly Termitonilla luteola Borgmeier, 1950 , in which the pronotum is narrower posteriorly (conspicuously in Nannusa ); Dilacera pronotum is more related to that of Nannusa , but lacking the longitudinal suture and also having anterior margin concave.

The abdomen is also distinct in Dilacera , flattened and widest at segments IV-VI, along with a broad and transverse paratergite on each side of the abdomen, which is entirely visible from dorsal view, and the highly modified paratergites VII and sternite VII comprises one of the most distinctive features of the genus; Termitonannina genera commonly have conical abdomen, except for Nannusa and Termitonilla ; yet none of them nearly resemble the abdomen of Dilacera .

Finally, it is worth mentioning that although it is possible to find some similarities in some structures compared to specific taxa in the subtribe; the new genus is so distinctive in many features that it looks like it has only the bare minimum to be included in the subtribe (4-4-5 tarsal formula and antenna with 10 antennomeres), which wonders the future possibility, when a phylogenetic analysis is performed, of supporting a new subtribe within Termitonannini .

Etymology: Derived from ancient Greek, δι (di-, “double”), and from Latin, lacer (“torn,” a cognate from lacinia). Thus, Dilacera means “double lacinia” in allusion to the double-lobed lacinia, unique in the subtribe. Feminine gender.