Masculine.

Helochares livornicus Kuwert, 1890: 38; subsequent designation by d’Orchymont (1939a: 154).

Body length ranging from 2.5–4.8 mm. Body shape oval in dorsal view, dorsoventrally slightly flattened, moderately convex in lateral view, with dorsal outline nearly evenly convex (Fig. 28); surface even and smooth, with usually shallow ground punctation (Fig. 28). Coloration usually dark brown seldom yellowish, uniform across body regions. Head trapezoid (Fig. 11G). Eyes relatively large, at most only slightly emarginated anteriorly, and not or only slightly projected from outline of head. Clypeus trapezoid, with anterior margin mesally emarginate; membranous preclypeal area visible when clypeus strongly emarginated. Labrum fully exposed. Mentum punctate or punctate laterally and medially obliquely striate; medial surface flat to depressed (Fig. 28C); anteromedial depression sometimes limited by low transverse carina. Antennae with nine antennomeres, with cupule slightly asymmetric and rounded. Maxillary palps slender, 1.2–1.5 × longer than width of head; maxillary palpomere 4 nearly 0.7 × length of maxillary palpomere 3; inner margin of maxillary palpomere 2 nearly straight, and outer margin curved along apical half. Pronotum evenly convex. Elytra with sutural striae, with outer margins slightly flared; ground punctures usually only shallowly marked, serial punctures absent and at least one median row of systematic punctures visible on each elytron (Fig. 28). Surface of prosternum usually flat, sometimes tectiform. Posterior elevation of mesoventrite with longitudinal carina; anapleural sutures sinuate, separated at anterior margin by distance similar to slightly shorter than anterior margin of mesepisternum. Metaventrite with posteromesal and posterolateral glabrous patches (Fig. 28C). Protibiae with spines of anterior row semi erect, relatively long, thick and sparse; apical spurs of protibiae relatively short and stout, not reaching apex of protarsomere 2. Metafemora with tibial grooves moderately developed; hydrofuge pubescence covering basal 4/5 of anterior surface of metafemora (Fig. 28C). Metatarsomeres 2–4 gradually decreasing in size, with two rows of spines on ventral surface; metatarsomere 2 slightly longer than 5, 5 shorter than 3 and 4 combined. Fifth abdominal ventrite emarginate at apex, with fringe of flat and stout setae. Aedeagus (Fig. 27B–D) with parameres at most only fused at base on dorsal surface; median lobe divided in dorsal and ventral plates; dorsal plate sclerotized along margins, medially membranous, membranes with papillae or denticles along apico-medial region; ventral plate as inverted Y, sometimes accompanied by basal median laminar sclerite; basal piece nearly as long as or longer than ventral length of parameres, always noticeable; gonopore not clearly visible.

Among Old World acidocerines, Crephelochares is unique in the presence of sutural stria. The Neotropical Chasmogenus is the most similar genus, as they both share this character (along with the more distantly related Neotropical genus Primocerus). They can be differentiated by the number of antennomeres (eight in Chasmogenus, nine in Crephelochares) and by the form of the aedeagus (trilobed in Chasmogenus, Fig. 25; divided and further modified in Crephelochares, Fig. 27B–D). The configuration of the aedeagus in Crephelochares is quite unique in Acidocerinae, especially because of the configuration of the median lobe and its inner membranes.

Afrotropical: Angola, Benin, Botswana, Burundi, Cameroon, Democratic Republic of the Congo, Gabon, Gambia, Ghana, Guinea, Kenya, Liberia, Madagascar, Mauritius, Mozambique, Namibia, Niger, Nigeria, Rwanda, Senegal, Seychelles (Aldabra), Sierra Leone, Somalia, Republic of South Africa, Sudan, Tanzania, Uganda, Zambia, Zimbabwe. Australasian: Australia (New South Wales, Northern Territory, Queensland), Fiji (Vanua Levu, Viti Levu), New Caledonia, Papua New Guinea. Indo-Malayan: Cambodia, China (Guangdong, Hong Kong, Taiwan, Yunnan), Indonesia (Borneo, Java, Papua, Sulawesi, Sumatra), Laos, Malaysia, Sri Lanka, Thailand, Vietnam. Palearctic: Bosnia, Croatia, Greece, Israel, Italy, Japan, Serbia and Montenegro, Spain, Tunisia, Turkey; Fig. 4.

Archangelsky (1997: 55) reproduced the larval descriptions by Anderson (1976), who reared larvae from adults of Crephelochares nitescens (as Helochares nitescens) in laboratory conditions. According to Anderson (1976: 223), females lay between 18 and 25 eggs, “located below the surface of damp soil, in a mossy hollow constructed by the adult; the hollow was always of the same size and shape and lined inside with loose silk. Eggs were deposited at right angles to base of nest, each covered by strands of fine silk attached to floor, walls and adjacent eggs”. The larvae hatch in 5–7 days and are predaceous (Archangelsky 1997: 55). “The larvae would not pupate in damp tissue paper, but only in moss. […]. The larvae pupated naked in the upper moss or in curled decaying leaves” (Anderson 1976: 223). Complete development lasted 24–33 days. Fikáček (2003) provided a diagnosis, pointed out the incompleteness of the descriptions and drawings offered by Anderson (1976), and commented on the unusualness of the habit of laying eggs on the ground by hydrophilid standards.

As for the adults, ecological information is very scarce. According to Hebauer (1992), C. livornicus (Kuwert) was collected in stagnant water with decaying plants and C. orbus (Watanabe) was collected in a rice field. The recently described C. parorbus (Jia and Tang) was also recorded from stagnant waters (Jia and Tang 2018).

The only species for which immature stages are known is Crephelochares nitescens [from Australia; immature stages were originally described as Helochares nitescens by Anderson (1976)]. Anderson (1976) described the breeding method he used, the eggs and egg case, first and third instar larvae and pupa, as well as the entire life cycle. Archangelsky (1997: 55) reproduced Anderson’s (1976) findings.

Crephelochares was originally described as a subgenus of Helochares by Kuwert (1890: 38). In 1904, Ganglbauer established Crepidelochares without justification or explanation. Later, d’Orchymont (1919c: 148) synonymized Crephelochares with Chasmogenus keeping Chasmogenus as a subgenus of Helochares. In 1986, Fernández reinstated Chasmogenus as a genus, with Crephelochares as a junior synonym. Subsequent authors alternately either treated Crephelochares as a subgenus or junior synonym. Hebauer (1992) removed Crephelochares from synonymy with Chasmogenus, and established it as a subgenus of Chasmogenus, discussing morphological features in support of this view, which he maintained in subsequent works (Hebauer 1995). However, Hansen (1991, 1999b) viewed the differences in antennomeres and the aedeagal complexity as “rather subtle” and maintained the two names as synonymous without subgeneric division. The phylogenetic analysis by Short et al. (2021), together with the morphological evidence offered by Hebauer, resulted in the recognition of the generic status of Crephelochares.

There are 29 species of Chephelochares described to date; some of the older species have long lists of synonyms. The most comprehensive treatment for the genus was by Hebauer (1992); the genus was then considered as a subgenus of Chasmogenus.

Crephelochares abnormalis (Sharp), C. africanus (d’Orchymont), C. balkei (Short)*, C. irianus (Hebauer)*, C. livornicus (Kuwert), C. mauritiensis (Balfour-Browne), C. molinai (Hebauer)*, C. nitescens (Fauvel), C. orbus (Watanabe), C. paramollis (Hebauer)*, C. patrizii (Balfour-Browne), C. punctulatus (Short)*, C. ruandanus (Balfour-Browne), C. rubellus (Hebauer)*, C. rusticus (d’Orchymont), C. rutiloides (d’Orchymont), C. rutilus (d’Orchymont), C. szeli (Hebauer)*. For species marked with an asterisk, paratypes were available.

Hebauer 1992: diagnosis, key to species, diagnoses, descriptions for 22 species, and genitalia drawings for 19 of them; Hebauer 1995: one new species from Namibia; Watts 1995: revision of the Australian species of the genus; Short 2010: revision of the species from the Southwest Pacific islands, describing two new species from Fiji and newly recording C. nitescens (Fauvel) for New Caledonia; Devi et al. 2016: redescription and lectotype designation for C. abnormalis (Sharp) with a discussion on its distribution and morphological variation; Short et al. 2021: generic status and phylogenetic placement.