Revision of the genus Eotrechus Kirkaldy (Hemiptera, Heteroptera, Gerridae), with descriptions of six new species Author Tran, Anh Duc https://orcid.org/0000-0001-9605-0739 Faculty of Biology, University of Science, Vietnam National University, Hanoi, 334 Nguyen Trai, Thanh Xuan, Hanoi, Vietnam tran.anhduc@hus.edu.vn Author Zettel, Herbert https://orcid.org/0000-0002-7760-0472 Herbert Zettel, 2 nd Zoological Department (Entomology), Natural History Museum Vienna, Burgring 7, 1010 Vienna, Austria Author Sites, Robert W. https://orcid.org/0000-0002-3895-813X Enns Entomology Museum, University of Missouri, Columbia, MO 65211, USA text Deutsche Entomologische Zeitschrift 2023 2023-03-16 70 1 69 111 http://dx.doi.org/10.3897/dez.70.97117 journal article http://dx.doi.org/10.3897/dez.70.97117 1860-1324-1-69 99BBA4C8ED2048879952B61CC25309D4 CA0CBE818BFA5DFA80DBD42521D5DBE3 Eotrechus fansipan J. Polhemus, Tran & D. Polhemus, 2009 Fig. 25 Eotrechus fansipan J. Polhemus, Tran & D. Polhemus, 2009: 32-34, figs 1, 4-10, 17 (type locality: Lao Cai, Vietnam). Material examined. Vietnam •, 8 ♂♂ , 8 ♀♀ (apterous); Lao Cai Province , Sa Pa , Cat Cat , Ho stream (feeder stream of Muong Hoa stream); 22 Apr. 2011 ; Dinh N.H. et al. leg.; DNH11.02; ZVNU • 1 ♂ , 1 ♀ (apterous); same locality as preceding; 27 Oct. 2020 ; Tran A.D. leg.; TAD20-23; ZVNU • 3 ♂♂ , 1 ♀ (apterous); Lao Cai Province , Sa Pa , Sin Chai , Muong Hoa stream; 22 Apr. 2011 ; Dinh N.H. et al. leg.; DNH11.03; ZVNU • 1 ♂ (apterous); Lao Cai Province , Sa Pa , waterfall and stream by roadside from Sa Pa town to Nui Xe , ca. 13 km from Sa Pa town ; 23 Apr. 2011 ; Dinh N.H. et al. leg.; DNH11.10; ZVNU • 5 ♂♂ (apterous); same locality as preceding; 30 May 2013 ; Tran A.D. leg.; TAD1320; ZVNU • 1 ♂ (apterous); same locality as preceding; 25 Oct. 2013 ; Tran A.D. et al. leg.; TAD1358b; ZVNU • 1 ♂ , 4 ♀♀ (apterous); same locality as preceding; 25 Oct. 2020 ; Tran A.D. & Nguyen V.V. leg.; TAD20-18; ZVNU • 3 ♂♂ , 2 ♀♀ (apterous); Lao Cai Province , Sa Pa , waterfall by roadside from Thac Bac waterfall to Nui Xe , ca. 500 m from Thac Bac waterfall; 31 May 2013 ; Tran A.D. leg. TAD1321; ZVNU • 1 ♀ (apterous), 1 ♂ (macropterous); Lao Cai Province , Sa Pa , waterfall by roadside from Thac Bac waterfall to Nui Xe , ca. 1 km from Thac Bac waterfall; 31 May 2013 ; Tran A.D. leg.; TAD1322; ZVNU • 3 ♂♂ , 3 ♀♀ (apterous); Lao Cai Province , Sa Pa , Sin Chai , Sin Chai stream, site 1; 27 Oct. 2013 ; Tran A.D. et al. leg.; TAD1363; ZVNU • 2 ♂♂ , 3 ♀♀ (apterous), 1 nymph; Lao Cai Province , Sa Pa , Muong Hoa stream, upstream of Sin Chai ; 26 Oct. 2020 ; Tran A.D. & Nguyen T.A.N. leg.; TAD20-22; ZVNU . Diagnosis. Size: apterous males, length 7.66-8.50 (holotype 8.50), width 2.48-2.74 (holotype 2.74); macropterous male, length 9.80, width 2.56; apterous females, length 8.55-9.50, width 2.77-2.87; macropterous female, length 9.54-9.60. Dorsum mainly brown, venter mainly light-brown. Mesosternum ca. 3.2 x (male) and 2.95 x (female) length of metasternum. Male: fore femur incrassate, slightly constricted before apex, basal part with broad tubercle bearing patch of minute, dark setae, flexor side of femur with a row of ca. 10 long, stiff setae; fore tibia slightly curved in the middle, long, stiff setae scattered on extensor side and denser at distal part; abdominal sterna III-VI medially depressed, sternum VII broadly depressed, distinctly longer than two preceding sterna combined, posterior margin emarginated into a notch about two-fifths of sternum VII length. Male genitalia: segment VIII longer than sternum VII, posteroventral margin almost straight; pygophore with small lateral tubercle, ventral surface convex in lateral view; caudal projection of pygophore short, plate-like, with dense patch of long, soft setae on ventrolateral sides, apical margin almost straight; paramere small, ovoid; proctiger trilobed, posterolateral lobes small, posteroventral surface with dense patch of long, brush-like setae. Female: fore femur more slender than in male, femur without basal tubercle, with ca. 12 long, stiff setae along flexor side; fore tibia almost straight; abdomen, in lateral view, tapering towards apex; sternum VII ca. 1.1 x length of two preceding sterna combined, not enclosing genitalia. Remarks. Four species, Eotrechus fansipan , E. pingae , E. luaae , and E. elongatus are closely related to each other, by sharing similarities in the structure of the fore leg and genitalia of the male. Polhemus et al. (2009) provided a comparison among three species, Eotrechus fansipan , E. pingae , and E. luaae . Herein, we provide further comparison, with the addition of E. elongatus (Table 2 ). Table 2. Comparative morphology of E. pingae , E. luaae , E. elongatus , and E. fansipan (modified from Polhemus et al. 2009 ).

Male	E. pingae	E. luaae	E. elongatus	E. fansipan
Fore tibia	almost straight	almost straight	almost straight	flexor side curved at middle
Abdominal venter	median groove from sterna II-VII, narrow and deep	median groove from sterna III-VII less conspicuous	median groove not distinct, sternum VII broadly depressed	median groove from sterna III-VI less conspicuous, sternum VII broadly depressed
Posterior margin of segment VIII	without median process	with small acute median process	angular medially	straight, without median process
Proctiger	- posterolateral lobes large	- posterolateral lobes large	-posterolateral lobes small	- posterolateral lobes small
	- without patch of long setae	- with patch of long setae on posteroventral surface	- with patch of long setae on posteroventral surface	- with patch of long setae on posteroventral surface
Pygophore	- short	- long and slender	- long and slender	- medium length
	- lateral tubercles large	- without lateral tubercles	- lateral tubercles indistinct	- lateral tubercles small
	- posterior plate short and broad	- posterior plate narrow, tapering towards apex	- posterior plate relatively narrow, tapering towards apex	- posterior plate short and broad
	- without ventrolateral patches of setae	- ventrolateral patches of setae less dense	- ventrolateral dense patches of setae	- with ventrolateral dense patches of setae
Pygophore in lateral view	- ventral margin rounded	- ventral margin broad and straight	- ventral margin more angular	- ventral margin rounded

Distribution. Vietnam: Lao Cai ( Polhemus et al. 2009 ) (Fig. 25 ).