Sipyloidea stigmata Redtenbacher, 1908

Prathapan, K. D., Anith, K. N., Faizal, M. H., Lekha, M. & Dhanya, M. K., 2008, A report on Sipyloidea stigmata Redtenbacher (Diapheromeridae: Necrosciinae) as the first phasmid crop pest in India and its redescription, Zootaxa 1959 (1), pp. 58-64 : 58-61

Sipyloidea stigmata Redtenbacher

( Figs 1 –12 )

Sipyloidea stigmata Redtenbacher 1908:546 (Holotype female, not examined, Natural History Museum, Vienna, Austria, No. 1094); Brock 1998: 60; Otte & Brock, 2005: 321; Zompro, 2005: 9.

Description. Female. Light green when live with light pink hind wings, abdominal sternites laterally dull white, abdominal tergites tinted brown beneath hindwings, tarsi light brown. Lateral band not distinct over leading edge of hind wings unlike in male. Either side of mesonotum with a light green longitudinal area with dark patches and dark border, extending from posterior end to slightly beyond middle.

Dry specimens dull brown with green tinge on anteroventral portion of head, forewings and abdomen ( Fig. 1 ). Antenna light brown with distal two or three antennomeres olivaceous in some specimens, joints of antennomeres lighter in color. Lateral band along pro- and mesonotum and anterior area of wings less distinct compared to male. Radius black in proximal 1/3 of forewing. Anal region of hind wings translucent brown with light pink veins.

Head nearly flat dorsally with a median longitudinal sulcus. Eyes projecting laterally. Pronotum slightly shorter than twice its width, with anterior margin slightly concave and posterior margin slightly convex. Pronotum with a median longitudinal sulcus and a deeper transverse sulcus anterior to middle, narrowed near anterior1/3. Pro- and mesonotum granulose, granulation being stronger on mesonotum. Mesonotum narrowed slightly ahead of middle, with a distinct median longitudinal carina; lateral band on either side converge towards median carina in narrowed region ( Fig. 3 ). Mesonotum with a row of luteous spots distinct anteriorly along lateral band besides a few scattered spots on disc. Abdominal segments 2–5 subequal in length, 6–9 each shorter than preceding segment; seventh strongly narrowed posteriorly, eighth strongly narrowed anteriorly; 10 subequal to nine; supra-anal plate indistinctly carinate along middle, project well beyond apex of 10; supra-anal plate connate with 10, suture separating them being evident only laterally. Cerci long, slender, slightly curved, slightly compressed laterally, projecting well beyond end of subgenital plate ( Fig. 4 ). Subgenital plate protruding up to end of anal (10 th) segment, slender with acute apex. Gonapophyses projecting beyond subgenital plate, not reaching apex of supra-anal plate ( Fig. 5 ). Legs without spines excluding minute ones in row along ventral carinae. Forefemur subequal to foretibia or foretibia slightly longer. Midfemur slightly longer than midtibia. Hindfemur slightly longer than hindtibia. First protarsomere slightly longer to shorter than combined length of next four tarsomeres. First mesotarsomere about 2/3 as long as next four tarsomeres combined. First metatarsomere slightly shorter than next four tarsomeres combined. Wings reaching near middle of 7 th abdominal segment.

Male. Living specimens are similar to female in color, but with a distinct lateral band on either side well developed along leading edge of hind wing. Longitudinal marking on mesonotum less distinct. Dry specimens dull green to light brown ( Fig. 2 ). Body with a tricolored lateral band on either side: band being black laterally, bright brown in middle and green mesally. Band originates on head in front of eye, extend over leading edge of wings and reach up to last tergite. Green mesal band merge with olivaceous color of dorsum and turns indistinct in dry specimens. Head, pro- and mesonotum with indistinct black blotches. Posterior veins of forewing tinted green. Head, antenna as in female. Thorax olivaceous ventrally, abdomen dark ventrally. Antenna brown with distinctly lighter joints. Anal region of hind wings as in females.

Head, pronotum as in female ( Fig. 6 ). Mesonotum narrowed near anterior 1/6, with a distinct median longitudinal carina ( Fig. 7 ). Mesonotum with a row of luteous pustulate spots along mesal margin of black band, spots being more evident anteriorly and a few scattered luteous pustulate spots on disc. Abdominal segments 2–5 subequal in length, sixth onwards each shorter than preceding one; 8–10 wider than seventh, 10 th narrower than ninth; tergites 6–9 with median longitudinal carina, carina extends to 10 th tergite indistinctly. Anal segment with U-shaped apical notch ( Fig. 8 ) with five sharp spines internally on either side. Cerci laterally flattened, apex inwardly curved ( Fig. 9 ). Poculum swollen, shiny, with short, moderately spaced setae. Vomer with a single point. Forefemur subequal to foretibia. Midfemur longer than midtibia. Hindfemur subequal to or longer than hind tibia. First protarsomere longer than next four combined. First mesotarsomere subequal to next four combined. First metatarsomere longer than next four tarsomeres combined. Wings reach beyond base of seventh tergite.

Egg. Dark grey. Surface coarsely granulate, variously sculptured with irregular dark patches or ridges, thin areas in between appear dark olivaceous ( Fig. 11 ). Capsule barrel shaped, polar end bluntly truncated; opercular end with a collar. Operculum with umbrella-like pseudocapitulum as large as operculum, its surface coarsely granulate, sculptured and sharply raised in middle ( Fig. 12 ). Micropylar plate slightly towards polar end, narrow, spindle shaped, ridged along middle ( Fig. 10 ).

Measurements (mm). Female (n=5): Total length 78.0–83.5 (80.54), antenna 54.5–61.0 (57.1), head 3.8 –4.6 (4.4), pronotum 3.2–3.8 (3.5), mesonotum 7.5–12.5 (10.8), metanotum 2.5–2.7 (2.5), median segment 1.3–1.5 (1.4), forewing 5.8–6.7 (6.4), hind wing 43.5–48.0 (46.5), forefemur 19.5–20.5 (20.0), foretibia 19.5 – 22.0 (20.4), foretarsus 8.0–8.8 (8.2), midfemur 13.5–19.5 (15.2), midtibia 16.8–12.0 (13.6), midtarsus 5.5–7.2 (6.1), hindfemur 18.5–20.0 (19.1), hindtibia 15.0–17.5 (16.2), hindtarsus 8.0–6.5 (7.7), cercus 2.5–3.2 (2.8).

Male (n=5): Total length 53.0–56.5 (54.6), antenna 54.5–58.5 (56.5), head 2.3–2.9 (2.6), pronotum 2.2–2.5 (2.4), mesonotum 8.5–9.5 (8.9), metanotum 1.5–1.8 (1.7), median segment 0.7–0.9 (0.8), forewing 2.8–3.7 (3.3), hindwing 27.0–29.5 (27.8), forefemur 15.5–18.0 (16.7), foretibia 16.5–18.5 (17.6), foretarsus 10.0–8.8 (9.5), midfemur 7.3–17.5 (12.6), midtibia 6.7–12.0 (10.5), midtarsus 6.8–5.3 (5.7), hindfemur 16.0 – 17.3 (16.7), hindtibia 16.0–17.7 (16.9), hindtarsus 6.0–8.0 (7.5), cercus 1.0–1.1 (1.0).

Egg (n=5): Length 2.11–2.33 (2.21), height 1.32–1.49 (1.42), width 1.13–1.37 (1.27), diameter of operculum 0.89–0.96 (0.91).

Material Examined. 1♀, 1♂ INDIA Kerala Nelliampathy 6.v.2008 (K. D. Prathapan) , 7♀, 5♂ same data except the locality Thenmala and the date 23.viii.2008 ; 5♀, 9♂ same data except the locality Kulathupuzha and the date 27.viii.2008 (9 BMNH, 19 TCV) . Eleven eggs laid by a female from Kulathupuzha (11 TCV) .

Distribution. India (Karnataka, Kerala).

Biology. S. stigmata was first observed feeding on P. nigrum at Thenmala in Kerala in July 2006. Subsequently it was also collected at Ponkunnam and Nelliampathy Hills in Kerala. Observations at Thenmala and the nearby Kulathupuzha in August 2008 revealed an increase in its population to an economically significant level. One of us could collect 42 individuals in about 90 minutes in a homestead farm at Thenmala. This included nine adult males and one adult female. Both adults and nymphs feed on tender foliage resulting in defoliation of vines .

S. stigmata appears to be host specific. Besides P. nigrum , at Nelliampathy it was observed feeding on an unidentified wild pepper, Piper sp. So far it has not been observed feeding on any other plant. S. stigmata was reared on P. nigrum in the laboratory at Vellayani. Nymphs and adults had a distinct preference for tender leaves on plagiotropic branches. They fed by cutting from the margin. Eggs are dropped down casually. Eggs laid by both mated and unmated females in captivity hatched on 35 th day. A male became adult on 43 rd day after undergoing 5 larval instars. A female became adult on 48 th day after undergoing 6 larval instars. The female lived longer than male and died on 55 th day after the final moult.

General color of nymphs is green, first two instars being light yellow green. Some of the first instar nymphs had the egg shell hanging on one or either of the metatarsi as they could not pull it completely out of the egg shell during eclosion. Regeneration of legs lost during early nymphal instars was observed, the regenerated appendage being much shorter than the normal ones. Older nymphs and adults dropped down when disturbed. Females jumped down from the plant when approached with an unfurled black umbrella. Jumping is rarely reported in phasmids, however, a Sipyloidea sp. from Thailand has been reported with this behaviour ( Burrows and Morris, 2002). In general, females were fewer in number compared to males.

Significant increase in population of S. stigmata was observed at Thenmala over the last two years. Apparently it is becoming an economically important pest of black pepper in the Western Ghats region in south India, which happens to be the centre of origin of the crop and the majority of black pepper produced in India is from this area. Parthenogenetic mode of reproduction enhances the possibility of outbreaks of the insect. This necessitates development of appropriate management tactics. S. stigmata was observed between the altitudes 120–1220 m and it was absent in the plains and coastal areas. Unavailability of tender leaves during dry season could be the limiting factor here.

Figures

FIGURES 1–2. Sipyloidea stigmata: 1. female, 2. male.

FIGURES 3–5. Sipyloidea stigmata, female: 3. mesonotum, dorsal view; 4. apex of abdomen, dorsal view; 5. apex of abdomen, lateral view.

FIGURES 6–9. Sipyloidea stigmata, male: 6. head, lateral view; 7. mesonotum, dorsal view; 8. apex of abdomen, dorsal view; 9. apex of abdomen, lateral view.

FIGURES 10–12. Sipyloidea stigmata, egg. 10. dorsal view; 11. lateral view; 12. operculum.