Agraphydrus coomani ( Orchymont, 1927 )

Komarek, Albrecht & Hebauer, Franz, 2018, Taxonomic revision of Agraphydrus Régimbart, 1903 I. China and Taiwan (Coleoptera: Hydrophilidae: Acidocerinae), Zootaxa 4452 (1), pp. 1-101 : 34-36

Agraphydrus coomani ( Orchymont, 1927)

(Figs. 17, 18, 19, 52, 97, 139)

Helochares (Agraphydrus) coomani Orchymont 1927: 248 .

Agraphydrus coomani ( Orchymont, 1927) ; Watts 1995: 115.

Enochrus ryukyuensis Matsui 1994: 217 . Syn. n.

Agraphydrus ryukyuensis ( Matsui, 1994) ; Gentili et al. 1995: 208.

Type locality. Vietnam, Hoa Binh Province, “ Lac Tho ”.

Type material examined: H. coomani Holotype Ƌ (ISNB): “Hoa Binh \ Tonkin \ de Cooman [on a yellow card “Coll. R. I. Sc. N. B. \ Nord Vietnam] | A. d’Orchymont det. \ Helochares (Agraphydrus) \ Coomani m. Type | Type [red label]”. Tonkin is an inofficial name for the northern part of Vietnam. Hòa Bình is the name for a province and it’s capital in Northern Vietnam. Orchymont (1927) specifies the type locality as “Lac Tho nr. Hoa Binh”. Paratypes: VIETNAM: 23 exs. (ISNB): same sampling data.

A. ryukyuensis : Holotype Ƌ (CEM): “[Japan] Kamize-Dam \ Tokunoshima T[own] \ Tokunoshima Is[land] \ Kagoshima Pref. [Ôshima Dist.] \ 18.VIII.1987 \ leg. E. Matsui | Agraphydrus \ ryukyuensis (Matsui) \ det. Matsui E. | Holotype”. Paratypes (CEM): JAPAN: 2 exs. (CEM): same sampling data; 1 Ƌ (CEM): Kagoshima Pref., AmamīÔshima Isl., Tatsugou Town, Yairi, 20.VIII.1987, leg. E. Matsui; 1 ex. (CEM): Kagoshima Pref., Amami- Ôshima Isl., Sumiyo Village, Kawauchi River, 21.VIII.1987, E. Matsui; 2 exs. (CEM): Okinawa Prefecture, Kunigami District, Okinawa Island, Ôgimi Village, Henan River, 16.VIII.1990, leg. E. Matsui; 1 ex. (CEM): Okinawa Prefecture, Ishigaki Island, Sokobaru, 7.VIII.1989, leg. E. Matsui; 1 ex. (CEM): Okinawa Prefecture, Ishigaki Island, Nishihama River, 12.VIII.1989, leg. E. Matsui; 1 ex. (CEM): Okinawa Prefecture, Ishigaki Island, Takada, 12.VIII.1990, leg. E. Matsui; 2 exs. (CEM): Okinawa Prefecture, Iriomote Island, Komi, 9.VIII.1990, leg. E. Matsui.

We have not seen the 17 paratypes from Taiwan (CEM): “ Daikan River , Daikei-chin, Tohen Pref., 25.XII.1992, E. Matsui leg.” ( Matsui 1994).

Additional material examined: CHINA: Fujian: 2 exs. ( NMW): CWBS 255 ; Guangdong: 2 ƋƋ ( NMW): CWBS 461 ; Hainan: 1 Ƌ ( NMW): CWBS 178 ; 1 Ƌ (NMW): CWBS 187; 64 exs. (NMW): CWBS 192; 1 Ƌ (NMW): CWBS 197; 11 exs. (NMW): CWBS 198; 3 exs. (NMW): CWBS 199; 2 exs. (NMW): CWBS 201; 54 exs. (NMW): CWBS 202; 2 exs. (NMW): CWBS 203; 15 exs. (NMW): CWBS 204; 5 exs. (NMW): CWBS 207; 3 exs. (NMW): CWBS 210; 31 exs. (NMW): CWBS 211; 3 exs. (NMW): CWBS 212; 7 exs. (NMW): CWBS 214; 50 exs. (NMW): CWBS 215; 12 exs. (NMW): CWBS 216.

TAIWAN: 2 exs. (CEM): “Tahhan [= Dahan] River \ Taoyuan Hsien \ TAIWAN \ 25.XII.1992 \ leg. Matsui, E.”. These specimens are almost certainly from the same locality as the other Taiwanese paratypes of A. ryukyuensis , but they are not labelled as paratypes.

Differential diagnosis. This species belongs to the group of species with apically infuscated maxillary palpomere 4 and absence of clypeal microsculpture, together with A. comes , A. confusus , A. ishiharai , A. jilanzhui

and A. robustus (see also Remarks under A. coomani ). Specimens from China differ from A. jilanzhui by yellow pronotum with mesal infuscation (pronotum black in A. jilanzhui ), from A. robustus , A. ishiharai , and A. jilanzhui by absence of apical extension of parameres, and from all species by shape of parameres (apex slightly bending mesad) and by finer elytral ground punctation. Similar aedeagus is present in A. wangmiaoi , a species with evenly oval body shape (versus widening posteriorly in A. coomani ) and unicolored maxillary palpomeres.

Description. Total length: 1.8̄ 2.2 mm; elytral width: 0.8̄ 1.2 mm; E.I.: 1.4, P.I.: 1.9̄2.2, elytra 3.0̄3.2× as long as pronotum. Habitus slender, elytra slightly widening posterior to midlength, moderately convex dorsally.

Coloration. Labrum, clypeus and frons black; clypeus with distinct, delimited, triangular preocular patches, about as wide as eye or larger, in few cases of very dark colored individuals preocular patches smaller than eye; maxillary palpi yellow, palpomere 4 with infuscation apically, distinct in most cases, rarely indistinct, very rarely absent; pronotum yellow, unicolored, or with undefined dark brown to black central patch with variable extension, or unicolored dark brown to black with narrow yellow lateral rim; elytra yellow, unicolored or with variably sized undefined infuscations; ventrites dark brown or black; legs yellow.

Head (Fig. 52). Clypeus with distinctly, evenly excised anterior margin; C.I.: 3.3, lateral length ratio clypeus/ eyes = 1.5̄1.6; microsculpture absent; ground punctures fine, interspaces 2̄3× as wide as punctures; systematic punctures moderately distinct. Eyes large, very slightly protruding. Antennae with nine antennomeres. Maxillary palpi slender, 1.1̄1.2× as long as pronotum in midline, 0.9̄1.0× as long as maximum width of clypeus; length ratio palpomere 4:3 = 1.2̄1.4, palpomere 4 slightly asymmetrical. Mentum with very fine, very widely spaced punctures, without microsculpture.

Thorax. Pronotal ground punctation as on head; systematic punctures moderately distinct. Elytral ground punctation as on head and pronotum or slightly finer; systematic punctures indistinct, arranged in four rows, mesal rows 1̄3 with strongly reduced number of punctures, not reaching anterior margin. Mesoventrite with mesal bulge.

Legs (Fig. 97). Pubescence present on proximal half of profemur or slightly more extended, on proximal 2/3 of meso- and metafemur; hairline oblique on profemur, slightly oblique on mesofemur, almost straight on metafemur.

Abdomen. Ventrite 5 with shallow to almost semicircular apical emargination.

Aedeagus (Fig. 139). Length: 0.33 mm. Phallobase shorter than parameres, about as long as wide, or slightly longer than wide, bending with obtuse angle towards narrowly rounded proximal apex; delimited manubrium absent; border between pigmented and unpigmented portion of ventral face indistinct, almost reaching proximal apex in midline. Parameres slender; margins weakly sigmoid, tapering towards blunt, asymmetrical apex, slightly inclining mesad; base slightly extending into phallobase, ventral face indistinct, slightly wider than dorsal face. Median lobe about as wide as one paramere, finger-shaped; apex bluntly rounded, not reaching apex of parameres; ventral face slightly wider and distinctly shorter than dorsal face; corona in subapical position; pair of styli present, arising from base of median lobe, not reaching its apex; basal apophyses moderately long, slightly inclining laterad, extending to distal third of phallobase.

Remarks. Specimens from Japan, originally described as A. ryukyuensis , do not differ from other specimens of A. coomani in the external and male genital morphology that lies within the spectrum of variability of this widespread species. Agraphydrus coomani varies in the pronotal coloration (between unicolored yellow and almost completely black) and slightly in the shape of the parameres (between more broadly and more narrowly rounded). The character states show a certain regional distribution pattern, but mixed populations occur: In Japan, some regions of Indonesia, the Philippines, and Papua New Guinea the pronotum of most individuals is almost entirely dark brown or black with narrow yellow lateral rim; in China, Taiwan, Laos, Thailand, and Vietnam the pronotum is mostly unicolored yellow or with small, indistinct central infuscation, very rarely the central patch has a wider extension. The parameres are more broadly rounded in many individuals from China, Laos, Thailand, Vietnam, Japan, some Indonesian islands, Malaysia, Australia; they are more narrowly rounded in some islands of Indonesia, and mixed populations occur in New Guinea and the Philippines.

Agraphydrus comes , A. confusus , A. coomani , A. ishiharai , A. jilanzhui , and A. robustus form a group of very similar species, sharing the following features: habitus slender (E.I.: 1.4̄1.6; P.I.: 1.9̄2.0); elytra widening posterior to midlength (in contrast to all other Oriental species of Agraphydrus ); distinct preocular patches present; eyes large (lateral margin of clypeus less than 2.0× as long as lateral margin of eyes); maxillary palpi slender, palpomere 4 infuscated apically; C.I.: 2.9̄3.3; number of nine antennomeres; clypeal microsculpture absent; metafemoral pubescence present on proximal 2/3–3/4; apical emargination present on abdominal ventrite 5; aedeagus slender with undefined manubrium.

Ecology. Collected in China between sea level and 800 m a.s.l. in rivers, including potamal sections, and streams, flowing through degraded forests, pastures, and cultivated land, on banks with shrubs, grass, sand, or mud; in various kinds of pools with aquatic vegetation; also in brackish water.

Distribution. Japan, China (Fujian, Guangdong, Hainan) and Taiwan to Australia. First record for China.