ON GERRIDAE AND NOTONECTIDAE ( HETEROPTERA HEMIPTERA : INSECTA ) FROM THE SILENT VALLEY , KERALA

Of the eight families of Gerridae, four namely the Gerrinae, Eotrechinae, Ptilomerinae and Halobatinae were represented in the collections. The study elicited the ·occurrance of five new species under three new genera, with one genus hitherto unrecorded in the country, namely Pleciobates Esaki. The family Notonectidae was represented by two species of the genus Enithares Spinola of the sub family Notonectinae.

This species can be easily indentified by the second tarsal segment of front leg longer than first; middle femur longer than the total body in male and about equal in female; the abdominal connexival spines in males surpass the first genital segment and not the abdominal tip and never do so in females.Remarks: L. anadyomene was flirst described from Pundaloya, Sri Lanka (Kirkaldy, 1901) and subsequently recorded from Sri Lanka and Philippine Islands (Distant, 1903), India (Dover, 1928), Sri Lanka (Lundblad, 1934).Sri Lanka and Southers Shan States (Hungerford and Matsuda. 1958) Malayasia and Singapore (Cheng and Fernando, 1969).During the present survey, 14 adults and 4 nymphs were collected, thus reported from Western Ghats after 63 years of gap.
Colour: Reddish browh.Pronotum dark orange yellow.Antennae and legs uniform in colour.Venter light.f.Female apical abdominal segments ventral view.g.Macropterous male apical abdominal segments dorsal view.h.Macropterous male apical abdominal segments ventral view.
Apterous male: 14.6 long; width across the mesoacetabula 4.2, brown and blac.kmarkings (Fig. la).Head with an irregular diamond marking and two lateral stripes, the lateral stripes in front of eyes black; venter pale; head protruding well beyond the eyes; anterior lobe of pronotum expanded laterally.Antenna shorter than body, lInd shortest and IVth longest.The relative length of antennal segments I-IV, 3.3; 2.3; 3.2; 3.4.Head including eyes wider than long.Eyes with inner margin emarginate.Rostrum slender, long, exteding anterior one third of mesonotum, third segment five times as long as the last segment.
Thorax: Pronotum a little wider than head including eyes, posterior margin broadly rounded.Pronotum with a dark median and two sub lateral lines, the median band continuous over the humeri.Mesonotum about four and half times as long as second sternite.Ompbalium distinct.
Front leg with femur not stouter than second femur, tarsal segments are equal in length and lined with minute hairs, claws arising near apex of inner side, first tarsus slightly longer than second.Hind leg with first tatsus more than two and half times as long as second.Measurement of leg segments; Fore leg: 5. 4,4.9,0.7,0.7;Middle leg: 17.3,14.8,2.0. 1.6;Hind leg: 16.9,11.4,1.8,0.7.Colour dark brown.
Abdomen: Abdomen elongate, connexival spines well developed, dark brown dorsally, with tips black, posteriorly black, surpassing tip of abdomen and pointed tips (Fig. I e).Eighth segment well developed with apical margin concave.Each dorsal abdominal segment with crescent shaped dark bands, embrasing a paler spot, underside of connexivum dark, venter light.
O. rhexenor, a hygropetric water stridder, mainly found in Western Ghats, at altitudes between 900 to 1200 metres above sea level (Anderson, 1980).They were found in a spring area an cliffs, resting, running & jum ping on rock surface covered by algal growth and a thin sheet of trickling water.The developmental stages of winged and wingless forms were also collected and mating pairs were also seen.This species was also found on wet cliffs much away from the water surface, seemingly a rather ephemeral type of habitat.Anderson (1980) reported that this species has been recorded as taken at light in Southern India.It is also interesting that the record of the The long do rsolateral projection of pygofer which is extending half their length beyond lateral wings of suranal plate as seen from above separates this species from all other known species of this genus (Hungerford and Matsuda, 1965)

Genus Pleciobates Esaki
The genus Pleciobates Esaki was first described from a single apterous female, P. tuberculatus Esaki, collected from Klang River, near Klang Gates, Selangor, Malaya (Esaki, 1930).Later, Cheng and Fernando (1969) while studying the taxonomy of Malayan Gerridae, described apterous and macropterous males.However, in the present study, it is interesting to note that Pleciobates, a malayan genus, has been reported from India for the first time and two new species are described.s.Pleciobates indicus sp.nov.
Colour: Pitch black, shining with dark brown markings.Antennae and legs black, venter grey with silvery pUbescence.
Apterous male: Head brown, a large broad black spot at the anterior part of head, black.Head protruding well beyond the eyes, basal margin of head brown, antenniferous tubercles, extreme apex of frons black, with minute brown pubescence.
Head including eyes 1.4 times wider than long.Eyes dark brown, shiny.Antenna black with a brown tinge, longer than body, segment I longest, longer than the rest of antennal segments together.IV shotest, III segment one and half times longer that II, II and IV equal in length, the relative length of antennal segments are 6.0, 1.25, 1.69, 1.2S.Rostrum pilose, dark brownis.hblack, I V segment shining black, extending upto the basal portion of prosternum, IVth segment twice as long as the second.
Thorax: Dorsal surface pitch black, shiny, a conspicuous central lonigtudinal brown marking arising from posterior margin of pronotum, not reaching the anterior part, lateral sutures of meso and meta-nota with silvery pubescence.Pronotum transverse, twice as wid as long, anterior and posterior margins straight, finely pubescent; prosternum brown, adpressed with silvery setae.Mesonotum long, twice as long as pronotum, moderately curved; mesosternum greyish black, adpressed with thick silvery pilosity.Metanotum about one third of meso-Dotum in length; metasternum very pale brown, thickly covered with silvery setae.Fore leg with two black longitudinal stripes, one on each side, a very short tubercle at apex towards inner margin, a constriction towards the inner margin near the apex on which tubercle is situated, setose ; tibia shorter than femur, with a row of nlinute tubercles towards the inner side; tarsi two segmented, first longest, one and half as long as the second, claws arsing near the apex of second.Middle leg long, slender, black, tinged coxae and trochanter brown, femur longer than body, a row of short curved spines on ventral side; tibia thin, half as long as femur, lined with long hair like setae along entire length; tarsi two segmented, brownish black, first very much longer than second.Hind leg with coxae, trochanter brown, femur long, slender, as long as middle femur; tibia short, four times as short as femur; tarsi two segmented, segments very short, first shorter than second.Measurements of leg segments; fore leg: 3.5, 2 .. 5, 1.0, 0.63 ; middle leg: 9.81, 4.25, 1.69, 0.25; hind leg: 9.81, 2.69, 0.13, 0.19.
Abdomen: Dorsal surface pitch black, shiny covered with minute silvery hair like setae, apex of last genital segment dark brown with a central broad black marking, shorter than thorax; connexi vum well developed, without spine.Parameres long, dark brown, curved, hairy, well protruding from IXth segment, tip pointed.Pygofer small (Fig. 2c).Endosoma with tip of apical plate broad, bifid; lateral plates paired, curved 'C' shaped; a small triangular paired plates in between apical part of dorsal plate and lateral plates (Fig. 2j).
Apterous female: General colour pattern and markings same as that of apterous male; differs from male in that the connexival spines well developed beyond the the Vlth abdominal tergum, connexiva black, shiny, spines brown and pointed.The female with a conspicious tubercle like process in the middle of the ridge at the posterior margin of metanotum ; other structures of female are similar to male.
Antennal segments I-IV measure: 3.0, 0.81, 0.88, 0.69.Measurements of leg segments; fore leg 2.81, 2.34, 0.97, 0.72; middle leg: 8.78, 4.72,1.81,0.34;hind leg: 8.97,259,0.13,0.19.Remarks: This speci~s is quite unique in the presence of the connexival spines not as long as the last two dorsal abdominal segments taken together and not directed inwardly without crossing with each other at apex in the females.The males are also different in the structure of fore femur and by the presence of indistinct connexival spines.
Colour: Shining black with light brown markings.Antennae and legs dark brownish black.Venter grey with silver pilosity.
Apterous male: Head brown, a large black fascia in the middle of the vertex anteriorly, a pair of black longitudinal streaks in front of eyes near the inner nlargin of eyes.Head protrudiug well beyond eyes.Basal margin of head, antenniferous tubercles, extreme apex of frons black: with brownish pubescence.Head including eyes 1.8 times wider than long.eyes dark brown, shiny.Antenna dark blackish brown, shorter than body, 1 st segment longest, longer than the rest of antennal segments together, IVth shotest, lInd segment distinctly shorter than third, IlIrd seglnent 1.6 times longer than the second, the relative length of antennal segments are, 3.25, 0.88, 1.44, 0.69.Rostrum pilose, brown, not surpassing the prosternum, segment III about three times as long as the IVth, latter black.Thorax: Dorsal surace of thorax pitch black, shiny, a conspicious broad brown marking in the middle of the pronotum, lateral sutures of meso-and meta-nota with silvery pubescence.Pronotum transverse, twice as wide as long, anterior and posterior margins slightly curved, Jateral margins concave with greyish pubescence, prosternum brown, pubescent.Mesonotum very large, about three times as long as the pronotum, moderately convex, a little widened posteriorly; metasternum grey, covered with silvery pUbescence.Front leg brownish black with brown femur, a row of small spines on the inner side to the entire length, a short" black pointed tubercle at the inner margin of the apical portion, a pair of black longitudinal stripe along its longitudinal axis, finely setose; tibia shorter than femur, the apical part slightly enlarged; tarsi two segmented, first segment one and half times longer than second, claws arising near the apex of the second.Middle leg long, slender, coxae and trochanter pale brown, rest of the leg dlrk brownish black, femur longer than body, a row of short curved spines on the ventral side towards the inner margin; tibia thin, lined with long hair like setae along its entire length; tarsi two segmented, first much longer than second.Hind legs with coxae and trochanter pale brown, rest dark brown with black tinge, femur long, thinner than second femur; tibia very short, less than one third the length of the femur; tarsi two segmented, segments very short, not easily sep3ra ble, first shorter than second.Measurements of leg segments; fore leg: 3.5, 2.5, 1.0, 0.63; middle leg : 9.8, 4.25, 1.69, 0.25 ; hind leg: 9.8, 2.69, 0.13, 0.19.
Apterous male: Head with a central broad black marking, frontal part of face dull yellow with a small thin longitudinal black fascia ; head protruding well beyond the eyes.Antenna shorter than body, black, basal part of 1st segment yellow; segment I longest, IVth shortest, IIJrd shorter than lInd, 1st about two and half times as long as the lind; the relative length of antenna} segnents are, 2.25, 0.94.0.88, 0.69.Head including eyes 2.2 times wider than long.Eyes overlapping one third of lateral part of pronotum.Rostrum yellow, apical of third and fourth segments black, short, surpassing slightly prosternum, third segments thrice as long as fourth.
Thorax : Pronotum a little wider than head including eyes, lateral margins concave, width of pronotum 3.2 times longer than its median length, finely setose and with black markings as shown in fig.4a.Mesonotum yellow, black or brownish markings, adpressed with minute brown setose, about 4.3 times as long as metanotum; metacetabular suture with black fasciae . .covered with brownish hairs.Omphalium distinct.Fore leg with femur twice as stouter as tibia, dark brown and with longitudinal black stripe, base and lateral portions yel10w without any prominent theeth or spines along inner margin; tibia pitch black armed with a conspicuous tooth at distal end; tarsi black, two segmented, second longest, four times as long as first, claws arising from half of apex of second.Middle leg black or brownish black, femur stouter than tibia; tarsic urved, first 1. 3 times as long as 2. 13,0.19,0.81 ; middle leg: 6.69 5.38,0.44,0.34 ; hind leg: 6.5,3.88, 0.38, 0.31.Abdomen: Abdomen short without connexival spine, black, seventh segment well developed.Endosoma with apical part of dorsal plate curved, with a small extension directed ventrolaterally; ventral plate with ductus seminicus; lateral plates paired, first pair distinct, partially sclerotized ; second pair clearly visible, thin and wavey.A small but well developed sclerite present between the apical part of of dorsal plate and the first pair of lateral plates.Parameres thin, curved, sickle shaped.
Apterous male: Head with a central black marking, posteriorly connected with black fasica along the posterior part of the inner margin of eyes; frontal part of face pale, a narrow longitudinal black fascia continued with central black marking to head; head protruding wen beyond the eyes.Antenna shorter than body, black, base of segment I pale, segment I longest, IVth shortest, lInd and IIIrd equaJ, segments I-IV measure, 2.31, 1.0, 1.0, 0.69.
Head including eyes two and half times wider than long.Eyes overlapping one third of lateral part of pronotum.Rostrum pale yellow with apical part of third and fourth segments black, short, surpassing posternum, third segment two and half times as long as the last segment.Thorax: Pronotum equal or a little wider than head including eyes, lateral margins concave, thrice wider than long, medianally finely pubescent, with black fascia as shown in Fig. Sb.Mesonotum with black fasciae, adpressed with minute brownish silvery long hairs, six times as long as metanotum, meta-acetabular area with black markings, setose ; omphalium indistinct.Fore leg with femur thrice as stouter as tibia, dark brown with a black longitudinal stripe, basal one third pale yellow, without any prominent teeth or spines, a very shallow notch without a tooth at the extreme apex towards Inner side, tibia brownish black, a small tooth like prolongation at distal end; tarsi two segmented, dark brown, first very short, about six times as short as the second.Second leg black or brownish black, femur stouter than tibia, tarsi two segmented, first longest, five times as long as the second.
Apterous female: Similar to apterous male in colouration and markings.

Macropterous female
Similar to macropterou8 male in colouration and markings; antenna shorter than body, segment I .. IV measure, t .88,0.75, 0.81, 0.63.Measurements of leg segmeats; fore leg: 2.06, 1.88, 0.94, 0.63; middle leg: 6.0, 4.44, 1.69, 0.31 ; hind leg: 5.69, 3.81,0.25,0.31(1960) considered that a satisfactory description of V aquarius awaits the capture of more specimens from South India.In the present expedition (April-May, 1980) two males, four females and three nymphs were collected from a road side jungle pool from Valiyaparathodu.at an altitude of 1000 metres.The following additional descriptions may be further useful in the identification of the species.
The occurrence of the Malayan element in the fauna and flora of Peninsular India is a widely recognised fact, but how this fauna and flora came to be so dispersed and isolated are the important points that require elucidation.It is interesting to note that in this study, out of nine species of gerrids, the genus Pieciobates, a typical Malayan genus, was recorded for the first time from Silent Valley and thereby from India.Similarly, Limnometra anadyomene which is known so far from Coimbatore, in South India & Srilanka, Philippine Islands, Malaya and Singapore, has been collected in goods numbers from this valley.Thus the presence of Indo-Ceylonese and Indo-Malayan forms in Silent Velley shows its uniqueness and proves the Valley as an important reservoir harbouring various isolated genera and species which may be truly autochthonous or biogeographical relicts.
All the type-materials are deposited in Zoological Survey of India, Southern Regional Station, Madras.They will be in due course transferred to National Collections of Zoological Survey of India, Calcutta.

SUMMARY
Nine species belonging to six genera of the family Gerridae were studied, of which five new species under three genera are described from Silent Valley.The genus Pleciobates Esaki originally described from Burma was recorded for the first time from India.Endosoma and parameres of Ventidius aquarius Distant are also studied for the first time.The family Notonectidae is represented by a single genus and two species, belonging to the subfamily Notonectinae.