DRYPTINAE Bonelli, 1810
Both British species are local and rarely encountered. Drypta is generally coastal while Polistichus occurs sporadically at light traps.
As considered here this group includes two tribes, Dryptini Bonelli, 1810 and Zuphiini Bonelli, 1810, both of which are often classified within a broadly inclusive Harpalinae Bonelli, 1810. A further tribe, Galeritini LeConte, 1853 is also often included but is otherwise generally considered as distinct. Dryptini is a widespread Old World group of almost 100 species in two genera; Drypta Latreille, 1797 with about 70 species, and Dendrocellus Schmidt-Göbel, 1846 with about 22 species, both are primarily tropical in distribution, extending south into Australia (a single Australian species of Drypta has become established in Hawaii), and only poorly represented in northern temperate regions; several species of Dendrocellus occur in warmer parts of Asia including India, Pakistan and China but none occur in Europe, and both Europe and Russia host only 2 species of Drypta, with the very widespread D. dentata (Rossi, 1790) common to both and extending north into the UK. These are very distinctive ground beetles, sometimes referred to as false bombardier beetles because of the superficial similarity, and the genera are very similar but species of Dendrocellus have pectinate claws and the forebody is usually longer whereas those of Drypta have smooth claws and are generally less elongate. Zuphiini Bonelli, 1810 includes about 300 species of 24 genera in four sub-tribes and is worldwide in distribution although only about 65 species occur in the Northern Hemisphere and most of these in warmer areas. Dicrodontina Machado, 1992 includes 3 species of the single genus Dicrodontus Chaudoir, 1872 and is endemic to the Canary Islands. Leleupidiina Basilewsky, 1853 includes about 90 species of 5 genera and is widespread in Old World tropical regions, extending south into Australia. Planetina Jedliéka, 1941 (variously included in the separate tribe, Galeritini) includes about 30 species of the Afrotropical and East Asian genus Planetes MacLeay, 1825. Zuphiina Bonelli, 1810 includes almost 200 species in 17 genera and is distributed worldwide. Zuphium Latreille, 1806 is the largest genus with about 75 species, it is mostly tropical but extends into northern temperate regions with 6 species in North America and 5 in Europe but it does not extend to the UK. The European fauna includes a further 14 species of 4 genera but only the very widespread Polistichus connexus (Geoffroy in Fourcroy, 1785) extends to the UK.
All species are small to medium sized and of typical carabid form with a narrow forebody and oval or elongate and near-parallel elytra, many are distinctively coloured or strikingly metallic and all may be recognized by form of the antennae; the scape is longer than the next two or three segments and all segments are setose. Many exotic species are very elongate, especially in the prothorax and the head anterior to the eyes and these tend to have long parallel-sided elytra and long slender appendages. In general they have a distinct and often narrow neck behind strongly converging temples, long cheeks and sharp protruding mandibles, large and convex eyes and smoothly convex vertex and frons. The pronotum may be cylindrical (Drypta) and unbordered or flattened dorsally with distinct lateral borders (Polistichus), and the elytra are obliquely to transversely truncate although this may not be convincing in some species. Many species are strongly and distinctly microsculptured, the entire dorsal surface is usually densely punctured and pubescent and the elytra have complete and punctured striae as well as an abbreviated scutellary striole. The appendages are long and slender; the second antennomere is diminutive and the others elongate and the maxillary palps are long and only weakly dilated. All species have long legs and can run fast, the femora are weakly clavate and the tibiae long and smooth, often pubescent or setose and usually with an apical fringe of setae and small, slender apical spurs and the front tibiae have a well-developed antennal cleaning notch. The tarsi are 5-segmented with all segments elongate or, in Dryptini, with the fourth bilobed and densely setose beneath-an adaptation to climbing vegetation in their wetland habitats. This very basic description will allow many of the species to be placed within the group but beyond the small though very representative UK fauna there is a very wide range of morphology, even in a single genus e.g. in Zuphium the eyes vary from large and convex with distinct facets to small and flat and lacking distinct facets to absent altogether. More generally the group includes many highly adapted subterranean species that lack or have very reduced eyes, lack pigments and have variously modified sensory setae, unusually some of these are fully-winged and are known to disperse by flight. All members of the large genus Parazuphium Jeannel, 1942, with about 45 species distributed throughout the Old World, are thus adapted to live in the soil or in caves; all are flattened, lack pigment and have variously developed eyes; 8 occur in Europe and the only species lacking eyes altogether is a Canary Island endemic.
Species of the Dryptini occur in wetland habitats, often among reed beds in otherwise open habitats and they will often be found communally, they are active predators and roam the substrate and climb stems and foliage in search of prey, they are fully-winged and fly readily. Adults occur throughout the year; they breed in the spring and often overwinter in large groups under debris, bark or among litter. Some exotic species occur in a wide range of wetland habitats ranging from densely vegetated floodplains to brackish and even saline habitats. Our only representative of the group, Drypta dentata, occurs in wetland habitats throughout Europe, The Middle East, North Africa and tropical Africa and is among the most common members of the group. Zuphiini also includes many wetland species but they occur more generally as well and many inhabit grassland and other open and densely vegetated habitats, many are soil dwelling and about 25 subterranean species have been described from all the major biogeographical zones except Africa and South East Asia. Most are fully-winged; they disperse by flight and are attracted to light traps. Our single representative, Polistichus connexus, is a rare species known from sites scattered across south and eastern England but it is probably either under-recorded or spreading as the warmest summer evenings produce records from light traps which may be from continental visitors or, which seems more likely given the widely spaced records, from established populations. Typical habitats include sandy or gravelly wetland situations or among soft clay and sand at cliff bases along the south coast.