Ptilomerella anderseni, Zettel, 2009

Zettel, H., 2009, Three new genera of Ptilomerinae (Hemiptera: Heteroptera: Gerridae) from Southeast Asia, Zootaxa 2046 (1), pp. 26-42 : 35-37

Ptilomerella anderseni sp. n.

( Figs. 10, 11 , 17, 19, 21, 24)

Type material. Holotype (macropterous, dealate male) and paratype (apterous female) labelled "S. Burma: Dawna Hills \ 2.050 ft, 27.x.1934 \ leg. René Malaise " ( NHRS).

Type locality. Myanmar, Kayin State, Dawna Hills , exact locality unknown, ca. 625 m a.s.l.

Description. Genus characteristics are not repeated here.

Macropterous male (dealate). Dimensions. Body length 6.4 mm. Maximum body width at meso-acetabula 2.1 mm. Head width 1.22 mm. Length of second antennomere 1.21 mm. Length of mesofemur 11.0 mm.

Colour. Body almost entirely pale yellowish brown ( Fig. 10 ). Head with vague brown V-shaped mark. Pronotum with broad black lateral stripes which are posteriorly extented along hind margin of propleura until coxal cavity. Metapleura with small black mark near humerus of pronotal lobe. Acetabula with rather small, triangular, brown marks distally. Metacoxa with brown mark at base. Anterior tergites hardly infuscated.

FIGURES 12–24. Ptilomerella gen. n. (12–16, 18, 20, 22, 23) P. akekawati sp. n., (17, 19, 21, 24) P. anderseni sp. n. (12) Head and pronotum, dorsal aspect. (13) Foreleg of male, posterior aspect. (14) Pygophore of male, ventral aspect. (15) Proctiger of male, dorsal aspect. (16, 17) Left paramere of male, lateral aspect. (18, 19) Vesica of male, lateral aspect (left side). (20, 21) Posterior part of female's abdomen, lateral aspect; (22) same, dorsal aspect; (23, 24) same, ventral aspect. All pilosities omitted. ds = dorsal sclerite, du = ductus seminalis, gc1 = gonocoxa 1, ls = left lateral sclerite, pr = proctiger, s6, s7 = sternite 6, 7, sls = left second lateral sclerite, t6, t7, t8 = tergite 6, 7, 8, vs = ventral sclerite.

Structural characteristics. Relative lengths of antennomeres: 2.9: 1 (= 1.21 mm): 1.2: 0.6. Pronotal lobe in the typical shape of the subfamily ( Fig. 10 ), completely matt, width at humeri 0.8 times length of pronotum + pronotal lobe. Lengths of leg segments relative to mesofemur: profemur 37, protibia 29, protarsus 9+5, mesofemur 100 (= 11.0 mm), mesotibia 53, mesotarsus 20+3, metafemur 106, metatibia 33, metatarsus 2. Profemur very slender, length 10.2 times maximum width near base. Mesofemur wiithout long pilosity. Metafemur slightly longer than metafemur (1.06 times). Measured dorsally along midline, abdomen 1.15 times as long as thorax. Paramere (Fig. 17) with weakly pointed hook, distal section slightly S-curved and relatively stout. Vesica sclerites (Fig. 19): recurved apical part of dorsal sclerite slender and long, at ventral curve with prominent process on right side; first lateral sclerites proximally slender, distally broad, almost of triangular shape, distoventral margin smooth; second ventral sclerites prominent, elongate, their bases approximately at distal end of first lateral sclerites.

Apterous female. Dimensions. Body length 7.4 mm. Maximum body width at mesoacetabula 2.6 mm. Head width 1.24 mm. Length of second antennomere 0.96 mm. Length of mesofemur 9.6 mm.

Colour. Pronotum with marks similar as in male. Mesonotum with narrow dark margins anteriorly and posteriorly, with distinct blackish midline, separated from mesopleura by broad, black line. Metanotum separated from metapleura by narrow line. Acetabula with triangular, brown marks. Metacetabulum with brown mark at base in addition. Abdominal tergites 2–5 almost entirely blackish. Proctiger dark brown.

Structural characteristics. Relative lengths of antennomeres: 3.2: 1 (= 0.96 mm): 1.2: 0.8. Pronotum width 2.0 times median pronotum length. Lengths of leg segments relative to mesofemur: profemur 39, protibia 29, protarsus 9+6, mesofemur 100 (= 9.6 mm), mesotibia 60, mesotarsus broken off, metafemur 103, metatibia 38, metatarsus 2. Profemur slender, length 10.3 times maximum width near midlength. Metafemur hardly longer than metafemur (1.03 times). Measured dorsally along midline, abdomen 0.95 times as long as thorax. Connexiva posteriorly slightly folded over tergites, terminating in almost acute angles (Figs. 21). All tergites distinctly wider than long; tergite 1 slightly convex, matt; tergite 7 larger than preceding tergites, medially 1.3 times as long as tergite 6. Apex of abdomen high (Fig. 21). Sternite 7 with unique modifications, dorsolateral margin beset with dense dark pilosity; distal section of sternite 7 with hind margin bearing dense, dark pilosity laterally, with narrow, transversely folded medial lobe (Figs. 21, 24) bearing dense, whitish pilosity at its hind margin.

Comparative notes. Ptilomerella anderseni sp. n. is very similar to P. akekawati sp. n., if only on external morphology. However, examination of the male's vesica sclerites (Fig. 19) yielded important, species-specific differences: lateral sclerites distally broad and without serrate distoventral margin; recurved apical part of dorsal sclerite more slender; second ventral sclerites more prominent, both elongate, both starting at distal ends of first lateral sclerites. There is also a small difference in the shape of the paramere, notably the stouter distal part, but that characteristic could be more variable, if more males from Myanmar become available to study. Females of the two species are very similar, too, but there are differences in size and folding of the distal lobe of sternite 7, which is longitudinally folded in P. akekawati sp. n., but transversely folded in P. anderseni sp. n. (comp. Figs. 20–24). Also this characteristic should be used with caution, because intraspecific variations have been observed in some Potamometropsis species where the grade of folding of the distal structures of sternite 7 seems to depend on the female's readiness for mating.

Distribution. Southern Myanmar: only known from the type area, the Dawna Hills in Kayin State.

Etymology. This species is named in the memory of Nils Møller Andersen. The epithet is a noun in the genitive case.

Figures

FIGURES 10–11. Ptilomerella gen. n. (10, 11) P. anderseni sp. n. (10) Habitus of macropterous male (holotype; body length 6.4 mm), dorsal aspect, appendages omitted. (11) Habitus of apterous female (paratype; body length 7.4 mm), dorsal aspect, appendages omitted. © NHMW Hemiptera Image Collection, published with permission.