Homalotylus Mayr

Tirunagaru, Krishnachaitanya, Sagadai, Manickavasagam & Kumar, Abhinav, 2016, Five new species of Homalotylus Mayr (Hymenoptera: Encyrtidae) - from India with a key to Indian species, Journal of Natural History 50, pp. 2369-2387 : 2370-2375

Homalotylus Mayr

Homalotylus Mayr, 1876: 752 . Type species Encyrtus flaminius Dalman , by designation of Ashmead, 1900: 377.

Synonymy. See Noyes and Hayat (1984); Hayat (2006).

Diagnosis

Female body relatively large, measuring 0.9 − 2.3 mm in length, body dark brown to fully black or orange-yellow to brown; some dark species with metallic lustre. Head with frontovertex evenly curved and gradually merging with face; ocellar triangle with apical angle acute or 90°; posterior ocelli very close to eye margins; antennal torulus separated from mouth margin by about one-third its own length; eye kidney shaped, dorsally elongate, nearly reaching occipital margin; malar space short, not longer than eye width and generally with a weak malar sulcus. Mandible 3-dentate, rarely with only 2 teeth; maxillary palp 4-segmented, labial palp 3-segmented. Antennal funicle 6-segmented; clava solid or 3-segmented with oblique truncation. Thorax slightly convex; pronotum entire; mesoscutum with complete notaular lines; mid tibial spur frequently conspicuously serrate, varying from a little shorter to distinctly longer than mid basitarsus; basitarsus usually with only line of ventral pegs, rarely with up to 2 rows; hind tibia not broadened and flattened or hardly so, varying from 6 – 10× as long as broad. Fore wing with marginal vein quadrate to slightly longer than broad; post-marginal vein length variable; stigmal vein long; centre of disc densely and finely infuscate with brown setae, about basal third and apical third with transparent setae. Mesopleuron clearly separated from gaster by propodeum which broadly touches hind coxa; side of propodeum with dense setae, these often slightly flattened, scale-like and silvery. Gaster with anterior margins of T2 – T6 medially incised and with a median, longitudinal membranous strip, that on T5 and T6 are rarely incomplete; syntergum broadly shallowly concave without median incision or median membranous strip; syntergum very short, moderately to strongly transverse, 1.8 – 4.6× as broad as long, usually with a broad apical, semicircular invagination giving it a truncate appearance, rarely apically rounded; sternites II – V of gaster generally with a median membranous strip; hypopygium reaching apex of gaster, anterior margin concave with a median projection, posterior margin varying from virtually straight to acute, with a shallow median invagination; ovipositor varying from not exserted to strongly exserted; outer plate of ovipositor triangular, about 3 – 4× as long as broad, with up to 8 subapical setae; ovipositor varying from about two-thirds as long as mid tibia to more than twice as long; second valvifer usually without any subapical setae, but with up to 2 when present; gonostylus free, from less than one-tenth as long as mid tibia to about as long (modified from Anis and Hayat 1998; Noyes 2010).

Male. Sexual dimorphism very little. It is difficult to differentiate the sexes in species with a non-exserted ovipositor. Antennal scape in some species with a concavity on dorsal surface. T7 of gaster relatively longer, cercal plates situated at about distal third of gaster. External genitalia with a tubular phallobase, with aedeagal apodemes contained within the phallobase; parameres absent or reduced; digiti well developed, each digitus usually with three denticles ( Anis and Hayat 1998).

Comments

Homalotylus can be differentiated from other encyrtid genera using the keys given by Tachikawa (1963) for Japan, Noyes and Hayat (1984) for the Indo-Pacific region, Hayat (1985, 2006) for India and the adjacent countries, and Trjapitzin (1989) for Palaearctic region.

Revised key to Indian species of Homalotylus (females)

1. Body completely dark brown to nearly black and partly with metallic shine, occasionally frontovertex and partly the scutellum testaceous yellow; hind legs, excluding tarsi, dark brown .......................................................................................... 2

– Body not completely dark brown; most of head, largely the axillae and scutellum, and sides of thorax yellow or yellow brown, occasionally with pale fuscous suffusions; hind legs, excluding tarsi, not completely dark brown ..................... 10

2(1). Pedicel about 3.2× as long as wide and as long as F1 and F2 combined ( Anis and Hayat 1998, fig. 1) ....................... ...................... H. longipedicellus (Shafee and Fatma)

– Pedicel at most 2.8× as long as wide and shorter than F1 and F2 combined ........... 3

3(2). Ovipositor at most 0.6× as long as mid tibia ................................................................. 4

– Ovipositor at least as long as mid tibia ............................................................................. 6

4(3). Hind tarsus dark brown; clava white (pedicel 2.26× as long as wide; scape 7.37× as long as wide (F1 – F6, rarely F1 – F5, dark brown to black) ………… H. hemipterinus (De Stefani) [= eytelweinii (Ratzeburg) misidentification, see Noyes 2010]

– Hind tarsus white; clava basal third or so dark brown to infuscate brown and distal two third or so whitish or clava black except paler apex (funicle always dark brown) ..................................................................................................................................... 5

5(4). Mid tibial spur not serrate; scape about 6.4× as long as wide; clava in basal third or so dark brown to infuscate brown and distal two third or so whitish ( Anis and Hayat 1998, fig. 5) ........................................ ...................................... H. flaminius (Dalman)

– Mid tibial spur serrate; scape about 8.8× as long as wide; clava black except apex paler (Figure (1b)) ........................................ ....................................... H. biharensis sp. nov.

6(3). Ovipositor about 2× as long as mid tibia; scape not more than 6.5× as long as wide (pedicel about 2.4× as long as wide; antenna with radicle, scape, pedicel and F1 – F3 dark black; F4 ventrally light brown, dorsally white; F5 – F6 and clava white (Figure (3b)) ............................................................................... H. montanus sp. nov.

– Ovipositor at most 1.3× as long as mid tibia; scape at least 7× as long as wide. 7

7(6). Scape at most 7.5× as long as wide ................................................................................... 8

– Scape at least 8.3× as long as wide .................................................................................... 9

8(7). Pedicel about 2.2× as long as wide; F1 – F2 dark brown, F3 – F6 and clava white; hind tarsi fully dark brown; fore wing with uniformly pale brown setae distad of infuscation, without an oval area of transparent setae ( Anis and Hayat 1998, fig. 35).................................................................................................... H. agarwali Anis and Hayat

– Pedicel about 2.7× as long as wide; F1 – F4 dark brown, F5 – F6 and clava white; hind tarsi white except apitarsus brown; fore wing with an oval area of transparent setae adjacent to distal margin of infuscation ( Anis and Hayat 1998, fig. 32) .................................................. .................................................. H. scymnivorus Tachikawa

9(7). Scape about 8.3× as long as wide; antenna blackish brown except clava white ( Anis and Hayat 1998, fig. 18); hind tarsus at least partially white.............................. .............................................................................................................. H. turkmenicus Myartseva

– Scape at least about 8.8× as long as wide; antenna with scape, pedicel and F1 – F3 dark brown, F4 light brown, F5 white, F6 and clava orange ( Figure 2 (a)); hind tarsus completely dark brown ............................. ............................. H. insularis sp. nov.

10(1). Pedicel not more than 1.5× as long as wide (ovipositor 2.0× as long as mid tibia; F1 2.0× as long as wide; antenna brownish black, F5 – F6 and clava white) ........... ............................................................................................................... H. mexicanus Timberlake

– Pedicel at least 2.0× as long as wide .. ............................................................................. 11 11(10). Ovipositor at most 0.6× as long as mid tibia ................................................................ 12

– Ovipositor at least 1.1× as long as mid tibia .. .............................................................. 13

12(11). Entire funicle ( Noyes 2010, fig. 243), mid femur and tibia dark brown..................... ............................................................................................................................. H. terminalis (Say)

– F5 – F6 white ( Anis and Hayat 1998, fig. 15); mid femur and tibia yellowish brown. ......................................................................................................... H. formosus Anis and Hayat

13(12). Scape at most 7.2× as long as wide. ................................................................................ 14

– Scape at least 8.5× as long as wide .................................................................................. 16

14(13). Ovipositor about 2.2× as long as mid tibia ( Figure 4 (d)); pedicel at least 2.7× as long as wide ......................................................................................... H. varicolorus sp. nov.

– Ovipositor at most 1.6× as long as mid tibia; pedicel at most 2.3× as long as wide .................................................................................................................................................. 15

15(14). Flagellum dusky yellow, becoming paler towards distal end of clava ( Anis and Hayat 1998, fig. 47); propodeum dark brown with faint bronzy shine; AOL 1.16× as long as OCL ............................................. ........................................... H. indicus (Agarwal)

– Flagellum with F1 – F4 dorsally brown, ventrally light brown, F5 – F6 and clava white ( Figure 6 (b)) propodeum medially yellowish brown, laterally light brown; AOL 1.40× as long as OCL ....................................................................... H. noyesi sp. nov.

16(13). F1 – F2 and base of F3 brown, rest of F3, F4 – F6 and clava white; fore tibia and tarsi yellow ............................................................... H. ferrierei Hayat, Alam and Agarwal

– F1 – F5 dark brown, F6 and clava white; fore tibia and tarsi brown............................. ................................................................................................................ H. albiclavatus (Agarwal)

Descriptions of new taxa Homalotylus biharensis Krishnachaitanya and Manickavasagam , sp. nov.

( Figure 1 )

Female

Holotype. Length, 1.9 mm. Body dark brown to black with metallic green shine ( Figure 1 (a)). Head with eyes and frontovertex with silvery white setae. Antenna with radicle brown, scape with yellow band at base, remainder dark brown, pedicel and F1 – F6 dark brown, clava brown except apex white. Mesosoma dark with metallic green shine; tegula basally white, remainder brown. Fore wing infuscate from parastigma to end of venation, sub-basally and apically hyaline, hind wing hyaline. Legs dark brown except mid and hind tarsi 1 – 3 white. Metasoma dark brown, ovipositor sheath dark with ovipositor pale yellow. Head in frontal view broader than high (60:57); in frontal view eye 1.6× as high as wide; frontovertex with punctate-reticulate sculpture, interantennal prominence, antennal scrobes with imbricate sculpture; mandible with 3 acute teeth. Antenna ( Figure 1 (b)) with scape slender, 8.75× as long as wide; pedicel 2.2× as long as wide; F1 1.25× as long as wide and slightly longer than F2 – F6; clava obliquely truncate, 2.4× as long as wide. Measurements: head height:width, 57:60; eye height:width, 36:23; frontovertex width 14; POL 6; OOL 0.5; OCL 4.5; AOL 7; scape length:width, 35:4; pedicel length:width, 10:4.5; funicle length:width, F1, 7.5:6; F2, 7:6.5; F3,6:6.5; F4,6:6.5; F5, 7:7; F6, 7:7; clava length:width, 24:10.

Mesosoma 1.4× as long as wide; mesoscutum 1.9× as wide as long; scutellum 1.25× as wide as long; pronotum and mesoscutum with imbricate sculpture, axillae and scutellum with punctate reticulate sculpture. Fore wing ( Figure 1 (c)) 2.8× as long as wide; costal cell 11× as long as wide; marginal vein clearly longer than wide; stigmal vein 2.2× as long as postmarginal vein. Mid tibia 3.2× as long as mid tibial spur; mid basitarsus with 16 pegs and 1.1× as long as mid tibial spur; mid tibial spur serrate. Measurements: mesosoma length:width, 65:47; mesoscutum length:width, 25:47; scutellum length:width, 28:35; forewing length:width, 165:58; costal cell length:width, 66:6; marginal vein length:width, 6:3.5; postmarginal vein length 6; stigmalvein length 13; mid tibia length 57; mid basitarsus length 20; mid tibial spur length 18.

Metasoma with posterior margin of T 1 more or less straight; T 2 – T 4 with posterior margin slightly convex; posterior margin of T 5 and T 6 concave; syntergum medially, broadly V-shaped; T 2 – T 5 each with an anterior, median incision. Hypopygium extending to apex of gaster; ovipositor ( Figure 1 (d)) slightly exserted and 0.9× as long as mid tibia. Measurements: metasoma length 57; exserted ovipositor length, 10; ovipositor length 50.

Material examined

Holotype, 1 f# (on slide under 4 cover slips) labelled ‘ INDIA: Bihar, Banka, Bounsi (N25.14° E86.56°), 08.i.2014, YPT, Abhinav Kumar ’ ( EDAU, Registration No. Enc /006/2015).

Male

Unknown.

Host

Unknown.

Comments

This species is similar to H. sinensis in having the ovipositor slightly to not exserted, whole antennal funicle black and pedicel at most 2.3× as long as wide, but differs in having ovipositor length, 2 mm; clava 3-segmented; scape 8.75× as long as wide; mid tibia 2.85× as long as mid basitarsus (ovipositor length, 1.8 mm; clava solid; scape 7.5× as long as wide; mid tibia 1.1× as long as mid basitarsus in H. sinensis ).

Etymology

This species is named after the type locality, Bihar .

Figures

Figure 1. H. biharensis F#: (a) Habitus image, (b) antenna, (c) fore wing, (d) ovipositor.

Figure 2. H. insularis F#: (a) Habitus image, (b) antenna, (c) fore wing, (d) ovipositor.

Figure 4. H. varicolorus F#: (a) Habitus image, (b) antenna, (c) fore wing, (d) ovipositor.

Figure 6. H. noyesi F#: (a) Habitus image, (b) antenna, (c) fore wing, (d) ovipositor.