Amemboa bifurcata, Basu, Srimoyee, Subramanian, K. A. & Polhemus, An. A., 2014

Basu, Srimoyee, Subramanian, K. A. & Polhemus, An. A., 2014, Two new species of Amemboa Esaki (Heteroptera: Gerridae) from West Bengal, India, Zootaxa 3774 (6), pp. 567-577 : 572-576

Amemboa bifurcata sp. nov.

( Figs.16–33 )

Type Material: Holotype. apterous male, INDIA: West Bengal, Jalpaiguri District, Kalikhola, stream flowing between Chapramari Wildlife Sanctuary and Gorumara National Park, Lat. 26.871688°N, Long. 88. 87443°E, alt. 168 m, 17.iii.2013, coll. Srimoyee Basu; Reg. No. 3132/H15.

Paratypes. INDIA: West Bengal: 4 apterous males, 10 apterous females, 4 nymphs, same data as holotype; Reg. NO. 3133/H15; 2 apterous males, Jalpaiguri District; Chilapata forest, Bania River, Lat. 26.606552 °N; Long. 88.40428°E, alt. 74m, 19.iv.2013, coll. Srimoyee Basu; Reg. No. 3134/H15.

Description: Apterous male ( Figs. 16 & 18 ).

Size: (Measurement of Holotype in brackets) Body length 3.23–3.62 mm (3.49 mm); maximum width across mesoacetabula 1.04–1.13 mm (1.10 mm).

Colour: Brownish black with yellow markings dorsally. Head yellowish with black markings as in fig. 16. Eyes reddish brown. Pronotum black with yellow marking as typical for the genus. Sub-medial yellow stripes on mesonotum narrow, not connected to the lateral stripes. Metanotum almost black, with silvery pubescence. Laterally, pleural broad, black stripe reaches a little more than half way of body, discontinued from mesoacetabula. Abdominal tergite II–IV entirely black, V–VIII black with a median yellow spot. Meso- and metaacetabula with silverish, shining, frosted areas. Antenna and legs yellowish brown. Venter yellow. Rostrum yellow with fourth segment black. Metasternum medially with dark brown triangular mark. A pair of broad, black, curved stripes start from mesosternum, continuing upto metasternum, as typical for the genus. Abdominal sterna II–VI dark brown. Sternum VIII yellowish.

Structural Characteristics: Head 1.2 times wider than long; length of head 0.57mm, width of head across eyes 0.71mm. Interocular width 0.42mm, 1.9 times as wide as eye width (0.22). Eye length 0.35mm. Antennae shorter than body-length; length of antennomeres 1–4: 0.76; 0.74; 0.78; 0.86mm. Rostrum 1.4mm, reaching beyond the forecoxa ( Fig.18 ), 1st, 2nd and 3rd segment with pilosity. Pronotum 1.8 times wider than length (W/L= 0.87/0.48). Length of meso-and metanota 1.22mm together and maximum widths 1.18mm. Posterior margin of metanotum sinuate. Head, pro-, meso-and metanota, abdominal tergites I–VI with golden short sub-erect hairs. Male fore leg ( Fig. 20 & 21 ): fore femur moderately incrassate, ratio of length and width 4.1 (0.99/0.24); with three black tuft of hairs, basal part with elongated patch of stiff sub-erect hairs, followed by one thin almost pointed patch of hairs and distally with one elongated patch of black, short hairs. Fore tibia modified with outer margin concave and inner margin with a prominent ridge near middle, covered with short dense pilosity. Fore tarsus with first segment shorter than second segment; claws sharply bent, curved. Mid leg longer than the hind leg. Mid and hind femur, tibia, tarsus with scattered spines. Abdominal sterna 2X as long as wide (L/W=1.0/0.48). Sterna II–VI combined; sternite VII little wider and longer than the rest. Measurements of leg segments are provided in Table 5 .

Male genital segment (Figs. 24 & 25). Abdominal sternum VIII 1.4 times as long as wide (L/W= 0.69/0.48), elongated, with silvery pubescence. Abdominal sternite VIII 1.4 times longer than width, almost rectangular with parameres projecting outward (length/width: 0.72/0.50). Pygophore and proctiger as in Figs. 30 & 31 . Pygophore oval-shaped, basally more widened, with densely arranged long hairs and modified distally into an elongated narrow process. Proctiger semi-circular in shape, hairy below. The length of lateral arms of proctiger 0.40mm, bifurcated at middle forming two slender arms, tip of these two bifurcations end bluntly; in dorsal view, it is widened anteriorly, and then gradually narrowed towards its posterior end ( Figs. 32 & 33 ).

Apterous female ( Figs. 17& 19 ).

Size: Body length 4.14– 4.28 mm; maximum width across mesoacetabula 1.33–1.36mm.

Colour: Similar as in apterous male, except, the sub-lateral yellow markings on meso- and metanota disconnected at middle and the dark mark on meso- and meta sterna. Sternum VII yellow with broad, round black marking at middle.

Structural Characterstics: Similar to apterous male. Head length 0.71 and width across eyes 0.81. Interocular width 0.45. Pronotum 1.76 times as wide as long (W/L=0.90/0.51). Concavity on posterior margin of metanotum wider. Fore leg (Fig. 22) relatively slender, dorsally with a black stripe, ratio of length and width 5.9 (1.18:0.20); inner margin of fore femora with densely arranged black hairs and with golden hairs distributed throughout. Fore tibia without any modification, but with numerous short hairs. Tarsal claws sharp, curved. Abdominal sterna elongated, broad, length 1.25 and width 0.64. Measurements of leg segments as in Table 6 .

Genital segment of female (Fig. 26 & 27): Sternum VII 1.28 times as long as wide (L/W=0.73/0.57), basally broad, traphaezoid, hairy below. Ovipositors (Fig. 27) are long with densely arranged spines on it. Proctiger round shaped, ends bluntly.

Macropterous male and female: Unknown.

Etymology. The male lateral projection of the proctiger in this new species is bifurcated in the middle, giving rise to two different parts, which is a defining character of this species. Hence, the specific epithet ‘ bifurcata ’ is derived from the unique form of the male genitalic structures.

Habitat. The type series of Amemboa bifurcata sp. nov. was collected from a slow flowing stream, Kalikhola, located in boundary between Gorumara and Chapramari forest of West Bengal, India. The paratypes of this new species were collected from Bania River, a tributary of Teesta River, flowing across the Chilapata forest of Jalpaiguri district, West Bengal.

Comparative notes: Amemboa bifurcata sp. nov. is closely related to A. dentata J. Polhemus & Andersen, 1984 , first described from Dehradun, Uttarakhand. We have examined a male paratype of A. dentata from the type locality and find the following differences involving the male forelegs and male genitalia: 1) The basal two hair tufts on the male fore femur are similar in both species, but A. bifurcata possess two tufts distally, consisting of an acuminate tuft just beyond the central concavity followed by a broad brushy tuft ( Figs. 18, 20, 21 ), whereas in A. dentata only the acuminate tuft is present; in addition, the basal section of the male fore femur is more strongly incrassate in A. bifurcata ; 2) In A. bifurcata , the pygophore is much wider than in A. dentata ( Fig. 30 ); and 3) in lateral view, the more ventral of the two bifurcated lateral arms of the proctiger is very slender in A. dentata , while being thicker and more massive in A. bifurcata ; in dorsal and ventral views, by contrast, the shapes of the ventral arms are similar in both species.

Figures

FIGURES 16 – 21. Amemboa bifurcata sp. nov., (16) Apterous male, dorsal view; (17) Apterous female, dorsal view; (18) Apterous male, ventral view; (19) Apterous female, ventral view; (20) Fore leg of male, dorsal view; (21) Fore leg of male, ventral view.

FIGURES 28 – 33. Amemboa bifurcata sp. nov., (28) Genital segment of male, ventral view; (29) Pygophore and proctiger, lateral view; (30) Pygophore, ventral view; (31) Proctiger, ventral view; (32 – 33) Male lateral arms of proctiger (two opposite views).

Tables

TABLE 5. Measurements (values in mm) of leg segments of apterous male (n = 7) of Amemboa bifurcata sp. nov.

Leg Femur	Tibia	Tarsus1	Tarsus2
Fore leg 0.82–1.04	0.87–0.98	0.14–0.17	0.23–0.27
Mid leg 2.65–2.99	1.90–2.10	0.71–0.81	0.38–0.43
Hind leg 2.41–2.73	0.99–1.13	0.37–0.48	0.32–0.36

TABLE 6. Measurements (value in mm) of leg segments of apterous female (n = 10) of Amemboa bifurcata sp. nov.

Leg Femur	Tibia	Tarsus1	Tarsus2
Fore leg 1.09–1.16	1.06–1.15	0.16–0.19	0.26–0.29
Mid leg 3.11–3.29	2.07–2.25	0.79–0.93	0.41–0.43
Hind leg 2.68–2.93	1.10–1.20	0.47–0.53	0.33–0.40