Pogonini Laporte, 1834

Muñoz-Santiago, José & Ortuño, Vicente M., 2022, Revision of the tribe Pogonini (Coleoptera, Carabidae, Trechinae) from the Ibero-Balearic region, European Journal of Taxonomy 846 (1), pp. 75-109 : 78-80

Tribe Pogonini Laporte, 1834

Diagnoses

Imagoes of Pogonini can be differentiated from the rest of Trechinae by the following characters: umbilical series complete, formed by approximately 12 setae disposed from the humeri to the apical region. Basal elytra border complete. Last labial and maxillary palpomeres fusiform. Tarsi glabrous and with a longitudinal dorsal sulcus.

Description

Length between 4.0 and 8.0 mm from the anterior margin of the labrum to the apex of the elytra. Tegument glabrous; metallic in most species, although in some it is totally or partially depigmented. Microsculpture polygonal. Head with eyes protruding, medium- or large-sized and in general convex. Neck absent or poorly marked. Front wide, with two supraocular sulci more or less long and deep depending on the genus (very poorly marked in Sirdenus grayii ). Two supraocular setae. Antennae long and filiform, pilose from the anterior half of the second antennomere; last antennomeres slightly wider than the first ones. A pair of clypeal setae; 6 dorsal setae in the anterior margin of the labrum (the external ones are longer than the inner ones). Mandibles with a small and thin seta inserted in the mandibular sulcus. Last labial and maxillary palpomeres fusiform, with small setae (except in the apical ones). Ligula with a pair of setae. Labium not fused with the prebasilar, with a central and conspicuous bifid-tooth provided with a pair of fine setae in the base. Pronotum clearly wider than the head (except in S. grayii ), convex and of variable morphology: cordiform or sub-cordiform and more or less transverse; the lateral sinuosity and the posterior narrowing are more marked in some species than in others. Hind and posterior angles of the pronotum in general protruding; the lateral sulcus is narrow, slightly more explanate in some species. The pronotum has two pairs of setae, one inserted at its widest region and another inserted near the hind angles. Basal foveae in general large and limited by a carinula which presents different grades of development between the species (absent in S. grayii ). Base of pronotum depressed, punctured (punctation is more marked in some species than in others) and almost rectilinear, always coincident to the basal elytra border. Elytra, in general, convex and parallel or sub-parallel. Shoulders not or hardly protruding; functional wings. Basal and lateral elytra border complete. Scutellum present. 8 th elytral striae punctured and well-marked until the apical region, where they are frequently very tenuous or obliterated; punctuation more or less deep depending on the species. Basal striole punctured, present between the elytral suture and the first stria. Umbilical series complete from the humeral to the apical region, formed by approximately 12 setae; the first 3–4 setae are inserted in the lateral sulcus while the rest are inserted along the 8 th stria. The 1 st stria presents a setigerous pore in its base. Up to 5 setigerous pores disposed along the 3 rd stria in all species (commonly 3); setigerous pores present also in the 5 th and/or 7 th striae in Pogonus (Pogonoidius) meridionalis . Fine preapical setae present at the end of the 2 nd and 5 th striae. Legs, in general, slender; of a different colour from the body in some cases. Tarsus with a longitudinal dorsal sulcus; protarsus of the males with the first and second tarsomeres dilated, pilose and provided with adhesive phanerae. Prosternum glabrous in Pogonus and Pogonoidius , pilose in Sirdenus . Metepimerum visible. Last abdominal sternite with 2 setigerous pores in the males and 4 in the females. Aedeagus with median lobe asymmetrical, and the basal orifice located on its right side. Form and length of the median lobe variable between species, with the apex, in general, rounded and directed down. The internal sac of the median lobe is covered by small squamae, visible under the microscope; in the resting state it is possible to observe folds and sclerotised pieces which are variable on its form and extension between the species and groups. Left and right parameres unequal, both of them with at least one seta inserted in the distal region (the number could vary between individuals and species). Left paramere well-developed, with a triangular or sub-triangular form. Right paramere reduced, narrow and more or less elongated; in some cases, it is elbowed or curved.

Distribution

The tribe Pogonini has a worldwide distribution; it is present in all zoogeographical regions, with the main diversity of species in the Palaearctic ( Grebennikov & Bousquet 1999; Choi et al. 2015; Bousquet 2017).

Remarks

The tribe Pogonini is a very well supported monophyletic group within the subfamily Trechinae , closely related to Tachyini Motschulsky, 1862, Bembidiini , Anillini and other tribes than with Trechini ( Maddison & Ober 2011; Maddison 2012; Maddison et al. 2019). The species of Pogonini show, in general, predaceous, thermophilous and diurnal behaviours ( Rueda & Montes 1987), although it is also possible to find them developing a sublapidicolous life ( Mateu 1947). Detailed phenology and larval instars are unknown for most Pogonini ( Matalin & Makarov 2008) , but some data are available for a small number of species ( Jeannel 1941; see Grebennikov & Bousquet 1999).

Maybe the best-documented feature of the species of Pogonini is their strict relationship with saline environments. This trait, combined with the extended hygrophilous character of all Trechinae ( Ortuño & Toribio 2005: 17–18) , implies that the most common habitats of Pogonini are the coastal regions, salt marshes and saline continental waters. For this reason, pogonines have been widely considered as halobiont elements ( Bousquet & Laplante 1997). It was suggested that this specialised lifestyle derived from the basal hygrophilous condition of the subfamily, and it was originated as a response to intense interspecific competition with other riparian relatives ( Rueda & Montes 1987). The results of breeding Pogonini species in laboratory obtained by Grebennikov & Bousquet (1999) suggested that the halobiont condition of these ground beetles is shared both for the pre-imaginal and the imaginal stages. With respect to the study area, although the term “halobiont” has been applied with different criteria by Iberian entomologists ( Vives & Vives 1978a; Ortiz et al. 1989), a high grade of specialization and adaptation to the life in saline habitats (sometimes extreme saline) have been recognised for the local species ( Vives & Vives 1981, 1986; Rueda & Montes 1987; Serrano et al. 1990; Novoa et al. 1998; Andújar et al. 2001, 2002; Pardo et al. 2008; among others).

Key to Ibero-Balearic Pogonini

1. Pronotum more or less transverse, always clearly wider than the head ........................................... 2

– Pronotum longitudinal, as wide as or barely wider than the head. Tegument partially depigmented; elytra parallel and almost cylindrical body. Small species, 4.0–5.0 mm ............................................ ........................................... Sirdenus Dejean, 1828 : Sirdenus (Syrdenopsis) grayii Wollaston, 1862

2. Supraocular sulcus deep and long, surpassing the level of the anterior supraocular seta and ending close to the posterior supraocular seta. 8 th and 9 th interstriae of the same width ................................ ......................................................................................................................... Pogonus Dejean, 1821

– Supraocular sulcus little deep and short, ending at the level of the anterior supraocular seta or barely surpassing it. 9 th interstriae wider than the 8 th .......................................... Pogonistes Chaudoir, 1872