Metrocoris compar ( White, 1883 )

Jehamalar, E. Eyarin & Dash, Swetapadma, 2021, Three new species of Metrocoris Mayr, 1865 (Heteroptera: Gerridae) from India and establishment of species groups, Zootaxa 5082 (4), pp. 341-356 : 342-345

Metrocoris compar ( White, 1883)

( Figs. 1A–R )

1883. Halobatodes compar White, Voy. Challenger Rept. Zool. , 7: 68.

1893. Metrocoris compar (White) : Dahl, Ergebn. Plankt. Exp., 2: 8.

1993. Metrocoris compar (White) : Chen & Nieser, Steenstrupia , 19 (2): 65 (in part).

2016. Metrocoris dinendrai Basu, Polhemus & Subramanian, Zootaxa , 4178 (2): 265. Syn. nov.

Material examined. INDIA, WEST BENGAL, Kalimpong District, 1 apt. ♂, 1 apt. ♀, Neora Valley National Park , Bhotag Khadka Tempola, 1952 m a.s.l. , 27.29306° N, 88.84556° E, 24.x.2019, Coll. S. Sheela. Reg. No. 11558/H15.

Diagnosis. Metrocoris compar can be identified by the pruinose abdominal terga III–V of the female ( Fig. 1B ); tergum II is hidden, except laterally and half of the tergum III is also hidden by tergum I medially in the female ( Fig. 1B ); the flexor region of the hind coxa of the female is posteriorly slightly produced with a fringe of medium-sized, curved setae ( Fig. 1I ); the flexor region of the hind trochanter is fringed with long setae (0.34), length gradually decreasing from the base ( Fig. 1I ); the proximal region of the lateral sclerite of the endosoma is curved upward in lateral view ( Fig. 1R ); the male paramere has medium-sized setae (0.07) ( Figs. 1M, N, O, Q ).

Redescription. Apterous male: ( Figs. 1A, C–G, J–R ). Body length 5.76, body width at mesoacetabula 2.82.

Colour. Dorsum of body black with yellowish-brown marks; broad black mark on head slightly narrow anteriorly and broad posteriorly, posterosublaterally connected with black mark near eyes; median black mark on head not bifid posteriorly ( Fig. 1A ); antennae and legs dark-brown to black; antennal tubercle black; base of first antennal segment yellowish-brown ( Figs. 1A, C ); rostrum dark-brown to black, except lateral region of first to third segments yellowish-brown; proacetabulum black ( Fig. 1C ); pronotum with T-shaped black mark, sublateral mark broad curved downwards, extended laterally and connected to lateral mark of mesonotum ( Fig. 1D ); small area near anterolateral region of pronotum below eye yellowish-brown ( Fig. 1A ); fore femur dorsally and ventrally with broad black stripe connected to apical black ring, extensor region dorsally yellowish-brown ( Figs. 1A, C ); mesonotal longitudinal medial and lateral dark marks connected to horizontal black marks anteriorly and posteriorly, mesonotal black marks broader than adjacent yellowish-brown marks ( Figs. 1A, D ); sublateral black mark of mesonotum not connected posteriorly to black mark between meso- and metanota, sublateral black mark broad posteriorly ( Figs. 1A, D ); mesopleural black mark not connected anteriorly and posteriorly with transverse black marks ( Fig. 1D ); mesopleural yellowish-brown mark extended up to sublateral region of mesosternum medially, apex extended anteriorly and posteriorly ( Fig. 1C ); yellowish-brown mark on metacetabulum uninterrupted ( Fig. 1J ); area above base of metacetabular region with a small yellowish-brown mark ( Figs. 1A, J ); thoracic venter black, except mesosternal yellowish-brown mark on mediolateral region ( Fig. 1C ); coxa and trochanter of all legs yellowish-brown, except flexor region of mid and hind trochanter black; mid femur dorsally with long thin brown stripe; dorsum of abdomen black, except connexival segments VI and VII, posteromedian region of tergum VII and lateral and posterior margins of tergum VIII yellowish-brown ( Fig. 1J ); venter of abdomen black, except from apical region of sternum VI to apex of abdomen yellowish-brown, except sternum VII basomedially and lateral region of pygophore dark-brown to black ( Figs. 1C, F ).

Structural characteristics. Body clothed with small black adpressed irregularly arranged setae; eyes covering anterior 1/3 of propleura; sterna V–VI clothed with long brown setae laterally; antenna without any characteristic setae; head laterally with two long black setae in front of eyes; eye width slightly less than posterior eye width. Pleural region of prothorax posteriorly with sparse long black setae; anteromedian region of mesosternum with some long setae, prominent in lateral view ( Fig. 1D ); fore femur slender, flexor region with two long setae and fringed with small and medium-sized setae up to shallow notch; mid femur shorter than hind femur; mesal region of mesoacetabulum with thin stripe of short adpressed silvery-white to golden-yellow setae ( Fig. 1J ). Abdominal terga I–VII and connexivum clothed with short silvery-white to golden setae; sternum VII distinctly longer than combined length of sterna V and VI; posterior margin of sternum VII concave ( Fig. 1F ). Terminalia: Tergum VIII large, distinctly wider than long, posterior margin straight with some medium-sized black setae; lateral margin of sternum VIII parallel-sided; sternum VIII distinctly longer than sternum VII; posterior region of proctiger visible from above ( Fig. 1E ), proctiger elongate, widened before mediolaterally ( Fig. 1L ); pygophore posteriorly round with fringe of long setae laterally ( Fig. 1P ); paramere falciform clothed with medium-sized setae, except base, apical part modified ( Figs. 1M–O, Q ), visible from outside of genital segments ( Figs. 1A, D, E, G, J ). Endosoma in lateral aspect: proximal region of dorsal sclerite with reflex angled process; median part of dorsal sclerite straight; accessory apical sclerite absent; accessory lateral sclerite thin surpassing level of proximal region of dorsal sclerite; lateral sclerite proximally bend upwards, tip slightly broad; ventral sclerite not surpassing level of lateral sclerite in lateral view ( Fig. 1R ).

Measurements. Head length 0.71, width 1.55; eye length 0.66, width 0.38, posterior eye width 0.39; synthlipsis 0.64; lengths of antennomeres I–IV 2.18, 1.13, 1.05, 0.71. Pronotal length 0.63, width 1.59; combined length of meso- and metanota 2.19; mesosternal length 2.62; metasternal length 0.11. Lengths of leg segments: foreleg: femur 2.67, tibia 2.32, tarsomeres I–II 0.22, 0.84; mid leg: femur 7.12, tibia 5.31, tarsomeres I–II 2.34, 0.37; hind leg: femur 7.48, tibia 5.10, tarsomeres I–II 0.41, 0.49; widths of fore, mid, hind femora 0.37, 0.28, 0.19. Length of abdominal tergum 2.27; length of abdominal terga I–VIII 0.25, 0.45, 0.22, 0.15, 0.16, 0.16, 0.23, 0.39; length of abdominal sternum 1.82; lengths of abdominal sterna II–VIII 0.12, 0.10, 0.07, 0.09, 0.10, 0.29, 0.41; pygophore length 0.59; combined length of abdominal sterna V–VI 0.19; width of abdominal tergum VIII 0.76.

Apterous female: ( Figs. 1B, H, I ). Body length 5.38, body width at mesoacetabula 2.94.

Colour. Similar to apterous male, except for the following characteristics: dorsum of abdomen black with terga III–V pruinose ( Fig. 1B ); abdominal sterna VI–VII brown ( Fig. 1H ).

Structural characteristics. Similar to apterous male, except for the following characteristics: flexor region of hind coxa posterolaterally very indistinctly protruded and with fringe of medium-sized setae ( Figs. 1B, I ); hind trochanter without any processes, flexor region of hind trochanter fringed with long setae, setal length gradually decreasing from base to apex; flexor region of hind femur basally without setal fringe; abdomen short, not surpassing apex of hind coxa ( Figs. 1B, H, I ); tergum II hidden by tergum I, except laterally and half of tergum III hidden by tergum I medially; connexivum folded posteriorly ( Figs. 1B, I ); genital segments completely concealed under sternum VII; sternum VII constricted laterally and folded backwards apically ( Fig. 1H ).

Measurements. Head length 0.85, width 1.59; eye length 0.67, width 0.41, posterior eye width 0.38; synthlipsis 0.66; lengths of antennomeres I–IV 2.47, 1.08, 1.15, 0.94. Pronotal length 0.59, width 1.62; combined length of meso- and metanota 2.61; mesosternal length 3.03; metasternal length 0.12. Lengths of leg segments: foreleg: femur 3.32, tibia 2.74, tarsomeres I–II 0.16, 0.89; mid leg: femur 8.55, tibia 6.50, tarsomeres I–II 3.06, 0.41; hind leg: femur 8.52, tibia 6.02, tarsomeres I–II 0.52, 0.56; widths of fore, mid, hind femora 0.40, 0.32, 0.21. Length of abdominal tergum 1.33; length of abdominal sternum 1.01; lengths of abdominal sterna II–VII 0.14, 0.11, 0.11, 0.10, 0.14, 0.42; combined length of abdominal sterna II–VI 0.60; combined length of abdominal sterna V–VI 0.25.

Distribution. India: Arunachal Pradesh, Himachal Pradesh, Sikkim, Uttarakhand, West Bengal. Elsewhere: Bhutan.

Comparative notes. Metrocoris compar is morphologically similar to M. darjeelingensis Basu, Polhemus & Subramanian, 2016 , by having a similar yellowish-brown mark on the mediolateral region of the mesosternum. However, M. compar differs from the latter species by the spatulate apex of the paramere in lateral view ( Figs. 1K, M–O, Q ), which is bulbous in M. darjeelingensis . The setal fringe on the female hind trochanter of M. compar is pronounced basally ( Figs. 1B, H, I ), whereas it is pronounced apically in M. darjeelingensis (see Fig. 60 of Basu et al. 2016).

Remarks. den Boer (1965) studied the syntypes of M. compar ( White, 1883) and designated a specimen figured by White (1883) as the lectotype and the other specimens as paralectotypes and figured the endosomal structure. The endosomal sclerites ( Fig. 1R ) of the male specimen of the present study from the Neora Valley National Park, Kalimpong District, West Bengal, the type locality of M. dinendrai Basu, Polhemus & Subramanian, 2016 , completely matches the illustration given by den Boer 1965 (see Fig. 29). Chen & Nieser (1993 b) studied the paralectotypes of M. compar and specimens from Sikkim, West Bengal, Uttarakhand, Bhutan and Myanmar. The illustration of the endosomal sclerites of M. compar given by Chen & Nieser (1993 b) does not match the illustration given by den Boer (1965). Chen & Nieser (1993 b) and Basu et al. (2016) overlooked the illustration of the endosoma of M. compar given by den Boer (1965) that clearly shows there are some cryptic species of M. compar occurring in the Himalayan region. Moreover, species such as M. darjeelingensis , M. issaci sp. nov. and M. josephi sp. nov. exist in northeast India and have a little morphological differences with M. compar . Hence the characteristics of M. dinendrai completely match those of M. compar given in the revisionary work of den Boer (1965); thus, we synonymize M. dinendrai Basu, Polhemus & Subramanian, 2016 under M. compar . The materials studied by Chen & Nieser (1993 b) should be re-examined and new species described since the illustration of M. compar given by Chen & Nieser (1993 b) is entirely different from that of den Boer (1965). The distribution of M. compar south of Brahmaputra River particularly in Myanmar is doubtful because M. compar is a Himalayan species distributed in Arunachal Pradesh, Himachal Pradesh, Sikkim, Uttarakhand, West Bengal and Bhutan. So the present study excluded its distribution from Myanmar. The specimen studied by den Boer (1965) from Mishmi Hills of Arunachal Pradesh located east to Brahmaputra River belongs to another species. Chen & Nieser (1993 b) also mentioned that specimens of M. compar from Myanmar have the hind femora longer than the mid femora and have a less darkened thoracic venter. Thus, it is evident that M. compar from Myanmar is not conspecific with the species from India. A thorough study of M. compar from the Himalayan region is needed since there would be possibilities of the occurrence of cryptic species.

Figures

FIGURES 1. Metrocoris compar, apterous form: A, male, dorsal view; B, female, dorsal view; C, male, ventral view; D, male, lateral view; E, male, abdominal tip, dorsal view; F, male, abdominal tip, ventral view; G, male, abdomen, lateral view; H, female, abdomen, ventral view; I, female, abdominal tip and coxa and trochanter of hind leg, dorsal view; J, male, abdomen, dorsal view; K, male, genital capsule, lateral view; L, male, proctiger, dorsal view; M–O, male, paramere tip, in different angles; P, male, pygophore, dorsal view; Q, male, paramere (tip broken), lateral view; R, male, endosoma, lateral view.