Epimetopus Lacordaire, 1854

Fikáček, Martin, Matsumoto, Keita, Perkins, Philip, Prokin, Alexander, Sazhnev, Alexey, Litovkin, Stanislav & Jäch, Manfred A., 2021, The family Epimetopidae (Coleoptera: Hydrophiloidea): review of current knowledge, genus-level phylogeny, and taxonomic revision of Eupotemus, Acta Entomologica Musei Nationalis Pragae (Acta. Ent. Mus. Natl. Pragae) 61 (1), pp. 1-34 : 28-31

Epimetopus Lacordaire, 1854

( Figs 2R–Z, a–l ; 3E–I, K, P ; 4E–G, I–J, N–P, R ;

5B, E–F, G–H, K, O–P ; 6I–R ; 16 )

Ceratoderus Mulsant, 1851: 1 . Type species: Ceratoderus graniger Mulsant, 1851 .

Epimetopus Lacordaire, 1854: 467 . New replacement name for Ceratoderus Mulsant, 1851 due to the homonymy with Ceratoderus Westwood, 1841 .

Sepidulum Leconte, 1874:47 . Type species: Sepidulum costatum Leconte, 1874 ; synonymized by Hඈ*©ඇ (1876: 251).

Diagnosis. Small to moderately large species (body length 1.2–3.7 mm); body reddish to black, without metallic sheen ( Figs 16A–F ); eyes completely divided into dorsal and ventral portion ( E. trogoides group; Fංκගඹൾκ et al. 2011: fig. 12) or not (remaining groups; Fංκගඹൾκ et al. 2011: fig. 11); anterior portion of clypeus not divided from posterior parts; labrum not strongly narrowed posteriorly ( Fig. 2R, X, g–i ); mandibular apex tridentate ( Figs 2S, Y, e–f ); apical maxillary palpomere long, strongly to weakly asymmetrical ( Figs 2T, Z ); mentum ca. as long as wide, without setae along anterior margin ( Figs 2V, j–l ); pronotum 0.7–0.8× as long as wide, hood covering head forming anterior third of its length; ventral surface of the hood with set of parallel ridges ( Figs 3F, H ); prosternum without median elevation, ca. 0.3× as long as procoxal cavity ( Figs 3E, G ); procoxal cavity closed posteriorly ( Figs 3E, G, I ); mesanepisterna narrowly separated by anterior portion of mesoventrite ( E. costatus group; Fig. 3K ) or meeting mesally ( E. mendeli group; Fig.

5B) (other groups not examined); mesoventrite posteromesally with high transverse ridge ( Fig. 3K ); metaventrite ca.

as long as mesocoxa, without large smooth elevated areas ( Figs 3K , 5B ); middle and hind femora without posterior spine; phallobase short and wide; parameres simple; median lobe flat, with a pair of ventral projections or without any projections ( Figs 6L–R ); sperm pump absent; male sternite IX U-shaped ( Fig. 6K ).

Identification. The genus was revised by Pൾ*©κංඇඌ (2012) who also provided a key to the species groups and illustrated all species.

List of species (56 described species) Epimetopus plaumanni species group Epimetopus costatus species group E. multiportus Perkins, 2012 Uruguay, Paraguay (Pൾ*©κංඇඌ 2012)

E. plaumanni ( Costa Lima, 1954) Brazil (Santa Catarina, Nova Teu-

E. acuminatus Perkins, 2012 Guatemala (Pൾ*©κංඇඌ 2012) tonia) (Cඈඌඍ*ò Lංආ*ò 1954, Pൾ*©κංඇඌ E. angustus Perkins, 2012 Panama, Venezuela, Ecuador, Peru 2012)

(Pൾ*©κංඇඌ 2012) E. vianai Balfour-Browne, 1949 Argentina (B*òඅൿඈඎ*©-B*©ඈඐඇൾ 1949,

E. apocinus Perkins, 2012 Mexico, Costa Rica (Pൾ*©κංඇඌ 1979, Oඅංඏ*ò 1986, Pൾ*©κංඇඌ 2012)

2012) E. vulpinus Perkins, 2012 Brazil (Rio Grande do Sul), Uruguay

E. arizonicus Perkins, 2012 USA (Arizona) (Pൾ*©κංඇඌ 2012) (Pൾ*©κංඇඌ 2012) E. ballatoris Perkins, 2012 Venezuela, Trinidad and Tobago

(Pൾ*©κංඇඌ 2012) Epimetopus lanceolatus species group

E. bifidus Perkins, 2012 Mexico (Pൾ*©κංඇඌ 2012) E. lanceolatulus Perkins, 2012 Brazil (Mato Grosso), Paraguay E. burruyacu Oliva, 1986 Argentina (Tucuman) (Oඅංඏ*ò 1986) (Pൾ*©κංඇඌ 2012) E. costaricensis Perkins, 1979 Mexico, Belize, Costa Rica, Guate- E. lanceolatus Perkins, 2012 Brazil (Mato Grosso) (Pൾ*©κංඇඌ 2012)

mala, Honduras, Panama (Pൾ*©κංඇඌ

1979, 2012) Epimetopus trogoides species group

E. costatus ( Leconte, 1874) USA (Texas, Arkansas) (Pൾ*©κංඇඌ2012) E. clandestinus Perkins, 2012 Brazil (Mato Grosso), Venezuela E. ecuadoriensis Perkins, 2012 Ecuador (Pൾ*©κංඇඌ 2012) (Pൾ*©κංඇඌ 2012) E. fisheri Perkins, 1979 Mexico, Honduras (Pൾ*©κංඇඌ 2012), E. deceptus Perkins, 2012 Brazil (Mato Grosso) (Pൾ*©κංඇඌ 2012)

USA (Arizona) (Pൾ*©κංඇඌ 1979) E. fimbriatus Perkins, 2012 Brazil (Mato Grosso) (Pൾ*©κංඇඌ 2012)

E. hintoni Balfour-Browne, 1949 Argentina (Oඅංඏ*ò 1986, needs confir- E. tridens Perkins, 2012 Brazil (São Paulo) (Pൾ*©κංඇඌ 2012)

mation), Bolivia (B*òඅൿඈඎ*©-B*©ඈඐඇൾ E. trogoides (Sharp, 1874) Brazil (Mato Grosso, São Paulo)

1949, Pൾ*©κංඇඌ 2012) (Pൾ*©κංඇඌ 2012); records by Rඈ*ö*ü*ò

E. inaequalis Perkins, 2012 Ecuador, Peru (Pൾ*©κංඇඌ 2012) (1969) from Brazil and by Oඅංඏ*ò E. lacordairei Orchymont, 1933 Bolivia, Brazil (Mato Grosso), Pa- (1986) from Argentina need verifi-

raguay (O*©*ö*üඒආඈඇඍ 1933, Pൾ*©κංඇඌ cation

2012) E. venezuelensis Perkins, 2012 Venezuela (Pൾ*©κංඇඌ 2012)

E. latilobus Perkins, 2012 Costa Rica (Pൾ*©κංඇඌ 2012) E. latisoides Perkins, 2012 Panama (Pൾ*©κංඇඌ 2012) Epimetopus tuberculatus species group E. latus Perkins, 2012 Colombia, Venezuela (Pൾ*©κංඇඌ 2012)

E. tuberculatus Rocha, 1969 Brazil (Minas Gerais) (Rඈ*ö*ü*ò 1969,

E. lobilatus Perkins, 2012 Costa Rica (Pൾ*©κංඇඌ 2012)

Pൾ*©κංඇඌ 2012)

E. microporus Perkins, 2012 Honduras, Panama (Pൾ*©κංඇඌ 2012) E. mucronatus Perkins, 2012 Mexico, Honduras (Pൾ*©κංඇඌ 2012) E. oaxacus Perkins, 2012 Mexico (Pൾ*©κංඇඌ 2012) Records of Epimetopus E. panamensis Perkins, 1979 Panama (Pൾ*©κංඇඌ 1979, 2012) from Africa and the Arabian Peninsula E. plicatus Perkins, 2012 Venezuela (Pൾ*©κංඇඌ 2012) Specimens examined. ZAMBIA: 1 ♀ (BMNH): Kabwe, Kasanka NP, E. punctipennis Perkins, 1979 USA (Arizona, Texas, Oklahoma),

12°32ʹ28ʺS 30°12ʹ42ʺE, light trap – Edwards funnel, 30.xi.–1.xii.2012,

northern Mexico (Pൾ*©κංඇඌ1979,2012) Smith & Takano lgt. SAUDI ARABIA: 1 J (NMPC): Jizan Prov., ʻWadi

E. rectus Perkins, 2012 Costa Rica (Pൾ*©κංඇඌ 2012)

Atoudʼ, 8.ii.2016, 17°48ʹN 42°22ʹE, 245 m, J. Bezděk & D. Král lgt.

E. robustus Perkins, 2012 Panama (Pൾ*©κංඇඌ 2012) E. simplex Perkins, 1979 Costa Rica, Nicaragua, Panama, Comments. Both specimens belong to the Epimetopus

Venezuela (Pൾ*©κංඇඌ 1979, 2012)

costatus species group, i.e. the group for which the mor-

E. spatulus Perkins, 2012 Peru (Pൾ*©κංඇඌ 2012) E. steineri Perkins, 2012 Ecuador (Pൾ*©κංඇඌ 2012) phology of the male genitalia needs to be examined for E. transversoides Perkins, 2012 Peru (Pൾ*©κංඇඌ 2012) species identification. The specimen from Zambia (Fig. E. transversus Perkins, 2012 Bolivia (Pൾ*©κංඇඌ 2012) 16E) is a female and hence cannot be identified. The speci- E. trilobus Perkins, 2012 Venezuela (Pൾ*©κංඇඌ 2012) men from Saudi Arabia ( Figs 16F–G ) seems to correspond Epimetopus mendeli species group to E. burruyacu , i.e. the species endemic to Argentina. E. angulatus Balfour-Browne , Bolivia (B*òඅൿඈඎ*©-B*©ඈඐඇൾ 1949, Both specimens were collected at light. We contacted the 1949 Pൾ*©κංඇඌ 2012) collectors of both specimens who excluded the possibility E. coleuncus Perkins, 2012 Argentina, Bolivia (? Oඅංඏ*ò 1986 as of confusing or mixing the samples with those from South

E. angulatus , Pൾ*©κංඇඌ 2012) America. The specimen from Saudi Arabia is from the same

E. flavicaptus Fikáček, Barclay Ecuador (Fංκගඹൾκ et al. 2011) collecting event (same collectors, date and locality data) & Perkins, 2011 E. graniger ( Mulsant, 1851) Colombia (Pൾ*©κංඇඌ 2012) as the four specimens of the South American (likely Ar- E. mendeli Fikáček, Barclay Peru (Fංκගඹൾκ et al. 2011, Pൾ*©κංඇඌ gentinian) Chaetarthria reported by Fංκගඹൾκ & Lංඎ (2019: & Perkins, 2011 2012) 251). Most likely, these specimens have been mislabeled. E. peruvianus Perkins, 2012 Peru (Pൾ*©κංඇඌ 2012) E. thermarum species group Discussion E. arcuatus Perkins, 2012 Paraguay (Pൾ*©κංඇඌ 2012) The aim of this study was to publish the newly accu- E. balfourbrownei Rocha, 1969 Brazil (Mato Grosso) (Rඈ*ö*ü*ò 1969, mulated data on the family Epimetopidae which became

Pൾ*©κංඇඌ 2012)

available due to the newly collected material. Fresh alcohol

E. clypeatus Perkins, 2012 Guyana (Pൾ*©κංඇඌ 2012) E. surinamensis Perkins, 2012 Suriname (Pൾ*©κංඇඌ 2012) specimens enabled us to provide the first DNA sequences E. thermarum Schwarz & USA (Arizona, Texas), Mexico, of Eumetopus and Eupotemus . The new material from Barber, 1917 Belize, Guatemala, Costa Rica, Africa made it possible to dissect some specimens and

Panama, Venezuela, (S*ö*üඐ*ò*©ඓ & perform morphological comparative studies based on

B*ò*©*ôൾ*© 1918, Rඈ*ö*ü*ò 1969, Pൾ*©κංඇඌ

all three genera. New records complementing the data

2012)

on the distribution of all three genera became available. the air bubble is usually partly formed with the help of the Yet, it is very clear that the knowledge about the family antenna (H*©*ôගඹൾκ 1950), and the antennal modifications remains rather limited in some aspects; these are defined in Georissidae and Epimetopidae may hence correspond

and discussed below. to the adapted way of the gas exchange not necessarily

indicating a close relationship of both families.

Phylogenetic position of the family. It was mention-

Larvae. Larvae are so far only known for a few species

ed above that there is an apparent and strong conflict

of the genus Epimetopus (Rඈ*ö*ü*ò 1967, 1969; Cඈඌඍ*ò et between the position of the Epimetopidae revealed by

al. 1988; A*©*ö*ü*òඇǤൾඅඌκඒ 1997; Fංκගඹൾκet al. 2011; Rඈmorphological and molecular characters. Analyses based

ൽ*©ංǤඎൾඓ et al. 2020) but unknown for the other two genera.

on morphology always place Epimetopidae as sister to

Epimetopus larvae are all characterized by the adaptations Georissidae , irrespectively of what kind of characters are

for the underwater processing of the prey by piercing and used, and whether adult or larval data are included (H*òඇඌൾඇ

sucking: the adapted form of the mandibles, the enlarge- 1991; Bൾඎඍൾඅ 1994, 1999; A*©*ö*ü*òඇǤൾඅඌκඒ 1998; Bൾඎඍൾඅ

ment of the epistomal lobes and the reduction of the labrum

& Kඈආ*ò*©ൾκ 2004; Bൾඎඍൾඅ & Lൾඌ*ö*üൾඇ 2005; Bൾ*©ඇ*ü*ò*©ൽ

(Rඈൽ*©ංǤඎൾඓ et al. 2020). They are often associated with

et al. 2009; Fංκගඹൾκ et al. 2012). In contrast, molecular

reductions of spiracles and the closure of the tracheal analyses, despite not being conclusive about the phylo-

system (Rඈൽ*©ංǤඎൾඓ et al. 2020). Similar morphology of genetic position of the Epimetopidae never place them

the head and mouthparts, associated with underwater prey close to Georissidae (Bൾ*©ඇ*ü*ò*©ൽ et al. 2006, 2009; S*üඈ*©ඍ

processing evolved independently in Epimetopidae and in

& Fංκගඹൾκ 2013; M*öKൾඇඇ*ò et al. 2014; Lඳ et al. 2020).

three unrelated groups of the Hydrophilidae (Fංκගඹൾκ et

If the molecular data are correct, it would imply that the

al. 2018, Rඈൽ*©ංǤඎൾඓ et al. 2020). Moreover, Rඈൽ*©ංǤඎൾඓ supposed synapomorphies of Epimetopidae + Georissidae

et al. (2020) noticed that the lineages sister to those with evolved in both groups independently, as a result of con-

piercing-sucking mouthparts often have very different vergent evolution. We document here that Epimetopidae

morphology of the head and a tracheal system well correinhabit moist sandy shores of streams of standing waters,

sponding to the usual hydrophilid morphology. In addition,

i.e. the same environment as most Georissidae (Mൾඌඌඇൾ*©

at least in two cases in the Hydrophilidae ( Laccobiini and 1965, 1972; Fංκගඹൾκ & F*òඅ*òආ*ò*©ඓං 2010; Lංඍඈඏκංඇ &

Berosini ), the lineage with piercing-sucking larval adaptati- Fංκගඹൾκ 2011; Lංඍඈඏκංඇ 2018) and some riparian groups

ons contains significantly more species than its sister clade

of Hydrophilidae (e.g., Chaetarthria Stephens, 1835 and

in which larvae process the food above the water. This Thysanarthria Orchymont, 1926 : Pൾ*©κංඇඌ 1976, Fංκගඹൾκ

observation resembles the situation in the Epimetopidae .

& Lංඎ 2019). Chaetarthria and Thysanarthria are deeply

The species-rich Epimetopus with 56 species has larvae nested clades of the Hydrophilidae (S*üඈ*©ඍ & Fංκගඹൾκ

with piercing-sucking mouthparts. Its sister Eupotemus 2013 ) and are not closely related to Epimetopidae . Still,

has only eight known species and the larvae are unknown.

they bear some of the characters considered as synapo-

Hence, we cannot exclude that larvae of Eupotemus and morphies of Georissidae + Epimetopidae : they have a very

Eumetopus may be not adapted for piercing-sucking food long antennal scape, a bulbose pedicel, strongly reduced

processing, and hence may look different from those of

(yet not totally absent) pubescence on the ventral body

Epimetopus in head and mouthpart morphology and in surface, reduced gula and hence fused gular sutures, and

the development of the larval tracheal system. The first they bear numerous digitiform sensilla on the base of the

instar larvae of Eumetopus and Eupotemus can be obtained maxillary palpomere IV (Fංκගඹൾκ & Lංඎ 2019). Moreover,

from the egg cases carried by the females and should be

the mentum of Thysanarthria bears series of long setae

studied in detail.

along its anterior margin (Fංκගඹൾκ & Lංඎ 2019: fig. 3A),

Egg cases carried by females. Egg cases are carried by strongly resembling the situation found in Eumetopus (Fig.

females of all three epimetopid genera, and hence represent 4D). These convergences with Hydrophilidae indicate that

a synapomorphy of Epimetopidae . Similar behavior is

the convergent evolution of these characters cannot be a

present in two unrelated lineages of Hydrophiloidea : the priori excluded for Georissidae and Epimetopidae . Addi-

Spercheidae (Fංκගඹൾκ 2019d) and the Helochares group tional studies on the biology and functional morphology

of the hydrophilid subfamily Acidocerinae (S*üඈ*©ඍ et al.

of both latter families are needed to understand whether

2021). The egg-carrying behavior is considered as derived their biology and the morpho-functional adaptations to

in the Hydrophiloidea (H*òඇඌൾඇ 2000), i.e., it evolved indedeal with the riparian environment are indeed identical

pendently in each mentioned lineage and may be adaptive.

or just analogous. For example, the pronotal hood is a

This seems to be corroborated by the slightly different way unique character shared by both families. The studies of

in which the egg cases are carried in each group (H*òඇඌൾඇ the function of the hood including the parallel ridges on

2000). The purpose of this adaptation and whether similar

its ventral side (see Biology of Epimetopidae above for

or clade-specific evolutionary pressures led to the evolution current hypotheses) and a detailed comparative study of

of this behavior remains to be tested.

these structures between Georissidae and Epimetopidae

Monophyly and internal topology of Epimetopus . Our may reveal useful information. The gas exchange is ano-

morphological analysis failed to reveal the monophyly of

ther unusual aspect which is shared by Georissidae and

the genus Epimetopus ( Figs 1B–C ). In contrast, the DNA- Epimetopidae : both clades lack the hydrofuge pubescen-

-based analysis indicated Epimetopus as monophyletic.

ce, which, in other Hydrophiloidea , holds the ventral air

The taxon sampling was different in both analyses. Hence, bubble (Fංκගඹൾκ 2019c, this paper). In Hydrophiloidea ,

both topologies may not be incongruent: the paraphyly of Epimetopus in the morphology analysis is caused by the member of the E. costatus group which is likely not involved in the molecular analysis. All Epimetopus species have posteriorly closed procoxal cavities, unlike any other epimetopids, based on which we consider the paraphyly of Epimetopus as unlikely. However, we cannot totally exclude it based on our data. Epimetopus is morphologically much more diverse than Eumetopus and Eupotemus .

This is evident even from our limited taxon sampling containing two Epimetopus species , i.e. representatives of the E. costatus and E. mendeli groups. The comparison of these two species revealed numerous differences, e.g., in the form of the prothoracic hypomeron (compare Figs 3E and G ), in the form and sculpture of the meso- and metaventrite (compare Figs 3K and 5B , for additional SEMs of E. mendeli see also Fංκගඹൾκ et al. 2011), in the form of the trochanters (with dorsal plates in E. costatus group, without such plates in E. mendeli ) and in the tarsal formula (5-5- 5 in E. mendeli , 4-4- 4 in E. costatus group).

These differences indicate that the E. costatus group may indeed have a rather isolated position within Epimetopus ; that needs to be tested by analyses with a wider species sampling covering all species groups of Epimetopus . Some other species groups also show apparent differences, e.g., in the eye morphology (completely divided in E. trogoides group, partially divided in other species; compare Figs 11 and 12 in Fංκගඹൾκ et al. 2011) and in the morphology of the male genitalia (with ventral projections likely corresponding to those of Eupotemus or without such projections; Figs 6L–R and genitalia illustrations in Pൾ*©κංඇඌ 2012). Additional studies are needed to understand the evolution of these characters within the genus and to confirm the monophyly of Epimetopus .

Figures

Fig. 2. Morphology of mouthparts and head appendages of the genera of Epimetopidae.A–I – Eupotemus Ji & Jäch, 1998: A, C, E, F, H – E. smithi sp. nov., B, D, G – E. limicola (Delève, 1967), I – E. cameroonensis sp. nov. J–Q – Eumetopus Balfour-Browne, 1949: J, L, M, N, P – E. schuelkei Jäch, 2002, Q – E. bullatus (Sharp, 1875), K, L*, O – E. sp. from Sri Lanka. R–Z, a–l – Epimetopus Lacordaire, 1854: R–W – E. mendeli Fikáček et al., 2011, X–Z, a–c – E. costaricensis Perkins, 1979, g, j – E. thermarum Schwarz & Barber, 1917, e, k – E. trogoides (Sharp, 1874), h – E. costatus group, f, i, l – E. punctipennis Perkins, 1979. Body parts:A–B, J–K, R, X, g–i – labrum; C, L, S, Y – mandibles; D, L*, e–f – mandibular apex; E, M, T, Z – maxilla; U – detail of basal part of ultimate palpomere; F–G, N–O, V, a–b, j–l – mentum and prementum; H–I, P–Q, W, c – antenna. Not to scale.

Fig. 3. Thoracic morphology of the genera of Epimetopidae. A–B, J, Q – Eupotemus smithi sp. nov.; C–D, L–O – Eumetopus schuelkei Jäch, 2002; E–F – Epimetopus mendeli Fikáček, Barclay & Perkins, 2012; G–I, P – Epimetopus costaricensis Perkins, 1979. A–I – prothorax in ventral view (B, D, F, H – detail of ventral sculpture of the pronotal hood; I – detail of closed procoxal cavity. J–L – meso- and metathorax in ventral view. M–N – elytron in ventral view (M – general view; N – detail of the ventral ridge, notice the spiny surface on inner face of the ridge (in) and on the elytral plectrum posteriorly of it (pl)). O – mesotrochanter. P–Q – details of pretarsus with the leaf-like empodial seta. Not to scale.

Fig. 4. Head and leg morphology of the genera of Epimetopidae. A–B, H, L – Eumetopus acutimontis Ji & Jäch, 1998; D, M – Eumetopus schuelkei Jäch, 2002; C, K–L, Q – Eupotemus smithi sp. nov.; F–G – Epimetopus punctipennis Perkins, 1979 (adopted from Pൾ*©κංඇඌ 2012); E, I–J, R – Epimetopus mendeli Fikáček, Barclay & Perkins, 2011; N–O – Epimetopus costaricensis Perkins, 1979. A – head in dorsolateral view (can – clypeal canthus causing the eye emargination); B–C – head in dorsal view (arrow – the ridge dividing anterior declined part of clypeus); D – mentum and maxilla; E – head in ventral view; F–G – occipital part of the head with median raised tubercle, dorsolateral view (arrows: parallel impressions corresponding to ventral ridges of pronotal hood); H–I – antenna, scapus largely omitted; J – labial palp; K – apical tibial armature, ventral view, mesothoracic leg; L – apical tibial armature and tarsus, ventral view, metathoracic leg; M – mesotibia; N–O – tarsus (N – posterior; O – anterior); P–R – metatibia, dorsal view. Not to scale.

Fig. 5. Morphology of Epimetopidae. A–B – ventral morphology: A – Eupotemus smithi sp. nov.; B – Epimetopus mendeli Fikáček, Perkins & Barclay, 2011. C–F – hind wings: C – Eumetopus schulkei Jäch, 2002; D – Eupotemus smithi sp. nov.; E – Epimetopus mendeli, adopted from Fංκගඹൾκ et al. (2011); F – Epimetopus costaricensis Perkins, 1979. G – dorsal part of the metathorax. H – scutellum. I–K – abdominal ventrites (I – Eumetopus schuelkei; J – Eupotemus smithi sp. nov.; K – Epimetopus mendeli). L–M – ovipositor (L – Eumetopus schuelkei; M – Eupotemus smithi). O – elytral punctation, slide-mounted elytra of Epimetopus costaricensis. P – female of Eumetopus acutimontis in ventral view, with the egg cases carried under the abdomen. Not to scale.

Fig. 6. Male genitalia and associated structures of Epimetopidae. A–H – Eupotemus Ji & Jäch, 1998 (A–F – E. smithi sp. nov.; G – E. cameroonensis sp. nov.; H – E. carinaticollis (Basilewsky, 1956)). I–R – Epimetopus Lacordaire, 1854 (I–N – E. mendeli Fikáček et al., 2011; O – E. cf. burruyacu Oliva, 1986; P – E. multiporus Perkins, 2012; Q – E. clandestinus Perkins, 2012; R – E. thermarum Schwarz & Barber, 1917). S–Z – Eumetopus Balfour-Browne, 1949 (S–Y – E. acutimontis Ji & Jäch, 1998; Z – E. bullatus (Sharp, 1875)).A, I, S – sternite VIII; B, J, T – tergite VIII; C, K, U – sternite IX; D, L, V – aedeagus dorsally; E, M, W – aedeagus laterally; F, N, X – aedeagus ventrally (basal part omitted in X); Y – sperm pump. Color coding: green – ventral projections of the median lobe; red – median lobe; blue – paramere (pale blue – dorsal lobe; dark blue – ventral lobe). Not to scale.

Fig. 16. Photographs of Epimetopus species, including two specimens of questionable provenance (E–G).A – E. flavicaptus Fikáček, Barclay & Perkins, 2011; B – E. deceptus Perkins, 2012; C – E. tridens Perkins, 2012; D – E. hintoni Balfour-Browne, 1949; E – Epimetopus sp. (ʻZambiaʼ); F–G – E. cf. burruyacu Oliva, 1986 (ʻSaudi Arabiaʼ) (F – dorsal view; G – aedeagus). Scale bars for A–F = 0.5 mm. A–D adopted from Pൾ*©κංඇඌ (2012).

Fig. 1. Distribution and phylogenetic relationships of Epimetopidae genera. A – summary of all known records of Epimetopidae, mapped by genera. Records for American Epimetopus adopted from Pൾ*©κංඇඌ (2012). B–E – phylogenetic relationship among genera based on morphological characters (B–C) and DNA data (D–E): B–C – strict consensus tree of the morphology-based maximum parsimony analysis (B – complete tree with bootstrap supports; C – Georissidae + Epimetopidae subtree with characters mapped). D – Bayesian maximum credibility tree based on cox1, 16S, 18S and 28S sequences, with posterior probability of particular clades. E – morphological characters mapped on the molecular topology of Epimetopidae constrained as sister to all other hydrophilid families following the topology by Lඳ et al. (2020).

Fig. 11. Male genitalia of the Eupotemus carinaticollis species group, holotypes.A–C – E. carinaticollis (Basilewsky, 1956); D–F – E. taianus sp. nov.; G–I – E. uluguru sp. nov. A, D, G – dorsal view; B, E, H – lateral view; C, F, I – ventral view.

Fig. 12. Habitus photographs of the species of the Eupotemus carinaticollis species group, holotypes: A–C – E. carinaticollis (Basilewsky, 1956); D–F – E. uluguru sp. nov.; G–I – E. taianus sp. nov.