Pseudoexeirarthra Park & Carlton

Park, Jong-Seok & Carlton, Christopher E., 2015, Pseudoexeirarthra, a new genus from New Zealand (Coleoptera, Staphylinidae, Pselaphinae), with descriptions of seven new species, ZooKeys 491, pp. 95-118 : 96-97

Taxon classification Animalia Coleoptera Staphylinidae

Pseudoexeirarthra Park & Carlton gen. n.

Type species.

Sagola spinifer Broun, 1895: 75; here designated.

Diagnosis.

Members of Pseudoexeirarthra can be separated from those of all other faronite genera by the following combination of characters: body length 1.8-2.8 mm; frontal sulcus broad and shallow, reaching level of the midline of eyes (Fig. 2A); lacking anterior and posterior frontal foveae (Fig. 2A); prosternum with lateral procoxal foveae (Fig. 2B); mesoventrite lacking promesocoxal foveae (Fig. 2C); tergites IV–VI with inverted triangle-shaped process on anterior margins (Fig. 2D); sternites IV–VI with basolateral foveae; female sternite VIII with pseudosternite (Fig. 2F); female sternite IX bearing pair of small process that each bear two long setae (Fig. 2G).

Description.

Body length 1.8-2.8 mm. Body reddish, antennae, legs, maxillary palpi and elytra paler (Fig. 1 A–J). Head. Antennae gradually clavate, reaching posterior margin of prothorax. Head bluntly triangular and longer than wide (Fig. 1 A–J). Apex of left mandible thicker than right (Fig. 2E). Frontal sulcus broad and shallow, reaching level of the midline of eyes, lacking anterior and posterior frontal foveae (Fig. 2A). Prosternum bearing median and lateral procoxal foveae (Fig. 2B). Mesoventrite lacking promesocoxal foveae, bearing lateral mesoventral and lateral mesocoxal foveae (Fig. 2C). Metaventrite with pair of lateral metaventral foveae (Fig. 2C). Tergites IV–VI with inverted triangle-shaped process on anterior margins (Fig. 2D). Aedeagus with bulky and round phallobase (Fig. 3 A–J). Parameres bearing setae along mesal margin for one-third to two-thirds length of parameres (Fig. 3 A–J). Female sternite VIII with pseudosternite (Fig. 2F). Female sternite IX bearing pair of small process that each bear two long setae (Fig. 2G).

Etymology.

The generic name refers to the superficial similarity to the genus Exeirarthra Broun.

Comments.

Members of this genus lack distinct external secondary sexual characters except on abdominal sternite IX. Male sternite IX is fragile, and partially concealed by sternite VIII, rendering it simple and reduced in appearance. Females possess a more robust, heart-shaped or rounded sternite IX that bears two pairs of long setae that are usually visible in ventral view. Female genitalia, including spermathecae, apparently are membranous and were not observed after clearing specimens using 10% potassium hydroxide.

Key to species of Pseudoexeirarthra gen. n.

Note. The key is largely based on male genitalia because most specimens are indistinguishable based on the external morphology. Antennal shape and eye size are apparently unique within species. However, apparent variations may result from viewing at inconsistent orientations among specimens. These characters are difficult to interpret consistently when performing identifications, but still useful in comparing types or specimens in series.