Lanka sahyadriensis, Prathapan & Viraktamath, 2008

Prathapan, K. D. & Viraktamath, C. A., 2008, The flea beetle genus Lanka (Coleoptera: Chrysomelidae) in India with descriptions of three new species and notes on the identity of the pollu beetle infesting black pepper, Piper nigrum, Zootaxa 1681 (1), pp. 1-30 : 15-19

Lanka sahyadriensis New species

( Figs 38–53 , 56)

Distribution. India (Karnataka, Kerala, Tamil Nadu).

Host plants. Piper mullesua Buch. -Ham. ( Figs 57, 58), P. nigrum ( Figs 59, 60), P. pseudonigrum Velayudhan & Amalraj ( Fig. 61) and P. wightii Miq. ( Figs 64–66).

Description. General color brown; in some specimens frons piceous; elytral suture narrowly piceous, apex of hind femora piceous; scutellum, anterior margin of elytra narrowly dark brown; metathoracic sternite darker along margins.

Vertex minutely punctate without moderate sized punctures. In lateral view, vertex and frons forms concave line. Supraantennal sulcus apparently stronger than supracallinal sulcus. Antennal callus not higher near postcallinal sulcus than near supraantennal sulcus. Anterofrontal ridge with a weak vertical carina along middle. Labrum with distance between middle two setiferous pores being slightly more than distance between lateral pairs. Antenna extending beyond half of elytra; fourth antennomere slightly shorter than third; fifth about longer than fourth; sixth slightly shorter than fifth; seventh antennomere distinctly longer than sixth; 7–10 gradually decrease in length; 11 th equal to or longer than tenth. Relative length of antennomeres vary. Antennomeres 3–5 slender, distal one or two antennomeres slightly wider than first.

Pronotum with stronger punctures posteriorly, lateral margin anteriorly slightly narrower than posteriorly in specimens from Nilgiris, anteriorly as wide as posteriorly in other specimens. Anterolateral callosity convex, as long as 1/3 of lateral margin including anterolateral callosity. Posterolateral callosity without minute setae on ventral side. Prosternum 3.6 times longer than width of intercoxal prosternal process, length of prosternum 9.4 times distance between anterior margin of prosternum to procoxal cavity. Intercoxal prosternal process depressed preapically with a ridge along middle, indistinctly raised along lateral as well as posterior margins. Mesoscutellum as wide as long, impunctate, minutely granulose. Mesosternum 1.2 times longer than width of intercoxal part, length of mesosternum 2.4 times distance between anterior margin of mesosternum to mesocoxal cavity. Mesosternum with lateral margin raised, posterior margin not raised, anterior half depressed on top, posterior half raised on top. Metasternum 1.3 times longer than prosternum. First protarsomere in female ventrally with short seta. Elytron with maximum width at middle, punctures form regular rows, punctures gradually turn indistinct beyond half hence difficult to count rows; distance between two adjacent rows 2–5 times diameter of a puncture in middle of disc. Metatibia indistinctly curved in lateral view, gradually widening from proximal end to slightly beyond half of it, then again narrowing. In dorsal view, maximum width at distal 1/3. Dorsal surface convex in proximal 1/4, rest of it more or less concave; lateral edge much higher than mesal edge in distal half. Second metatarsomere as long as half of first, slightly shorter than two times length of third; claw tarsomere about two times as long as third. All metatarsomeres together slightly longer than metatibia. Ridges on first abdominal ventrite reach half of its length, diverge in middle, converge distally ( Fig. 39 ).

Shape of spermatheca vary considerably. Pump smoothly curved near middle at right angles; a short denticle present on apex of pump in specimens from Karnataka ( Fig. 51 ), a well developed denticle present in specimens from Doddabetta Valley in Tamil Nadu ( Fig. 52 ) but such denticle absent in specimens from Nadu- vattam in Tamil Nadu ( Fig. 50 ); outer side distinctly concave in specimens from Karnataka, slightly concave to convex in specimens from Nilgiris in Tamil Nadu, inner side convex, more so in specimens from Karnataka; receptacle narrowed towards duct like a funnel in 3/4; duct originating at obtuse angle to long axis in specimens from Nilgiris, nearly at right angles to long axis in specimens from Karnataka, duct straight for some distance, thereafter curved, twisted five to six times; vaginal palpi narrowed from proximal end to about 1/3 rd of distance, then abruptly broadened; proximal end not curved as in L. ramakrishnai ( Fig. 49 ). Tignum with arrow-head shaped posterior sclerotization narrowing distally, similar to that of L. ramakrishnai ( Fig. 53 ). Shape of median lobe of aedeagus varies. In lateral view apex almost straight to recurved; ventral side with a longitudinal groove extending backwards from preapical depression evident in specimens from Nilgiri Hills, such a groove is absent in specimens from other localities ( Figs 41–43, 45–48 ). Aedeagus resembles that of L. ramakrishnai , but more distinctly narrowed preapically than that of L. ramakrishnai .

Measurements (n = 10). Length: 2.20–2.55 (2.39), width: 1.28–1.48 (1.39), body length-width ratio: 1.66–1.75 (1.72), length of pronotum: 0.60–0.75 (0.69), width of pronotum: 0.88–0.98 (0.94), width across eyes: 0.59–0.69 (0.64), transverse diameter of one eye: 0.23–0.29 (0.27), distance between eyes: 0.24–0.28 (0.26), distance between eye and antennal socket: 0.01–0.03 (0.02), distance between antennal sockets: 0.05– 0.08 (0.06), diameter of one antennal socket: 0.07–0.08 (0.08), length of aedeagus: 0.95, length of receptacle: 0.14, length of vaginal palpi: 0.29.

Types. Holotype ♂. Labels 1) SOUTH INDIA Western Ghats Tamil Nadu, Naduvattam 27.VI.2004 N11°28'24.2" E76°33'04" Prathapan K. D. Coll. 2) Lanka sahyadriensis sp. nov. Prathapan & Viraktamath, 2005 3 ) Holotype ( BMNH) .

Paratypes (71 specimens). 4♂, 3 ♀ data as holotype; Tamil Nadu , 1♀ Pykara , 22.viii.1989 (A. Riedel) ; 2♀, 1♂ Naduvattam , 19.x.2003 (Prathapan) ; 3 ♀ Longwood shola, 21.x.2003 (Prathapan) , 1♀ 23.vi.2004 (Prathapan); 2♂, 3 ♀ Coonoor , 23.x.2003 (Prathapan) . 1♂, 2 ♀ Doddabetta Valley , 24.vi.2004 (Prathapan) , 8 ♂, 2 ♀ 3.xii. 2005 (Prathapan). 1♂, 1 ♀ Karnataka, Madikeri , 19.XI.2003 1100m, dry forest, N12°28'20" E75°42'30" (Konstantinov, Prathapan, Saluk) ; 1 ♀ Madikeri, Temple Forest , 21.XI.2003 1138m, N12°27'31" E75°41'30" (Konstantinov, Prathapan, Saluk) ; 8♂, 16 ♀ Kottigehara , Alekhan Estate, 11. IX. 2004 (Prathapan) ; 5♂, 3 ♀ Kottigehara , 12. IX. 2004 (Prathapan) ; 1♂ Kottigehara, Alekhan Horatti , 19.X.2004 (Prathapan) ; 1 ♀ Kerala, Tirunelli , 22. iv. 2002 (Prathapan) ; 1 ♀ Kerala, No. 2, No data CIE A 12026 Lanka sp det. M. L. Cox (4 BMNH, 35 PNC, 5 UASB, 2 USNM, 10 NHMB, 4 EUJ, 4 KUJ, 1 LMRC, 6 PKDC) .

Other material examined. Kerala, Silent Valley National Park , 9♂, 6 ♀ Sairandhri 28.xi-1.xii.2006; 6♂, 4 ♀ Poochippara 3-4.xii.2006 (Prathapan) ( PKDC)

Etymology. The name sahyadriensis is derived from the Sanskrit name for the Western Ghats, a mega centre of biodiversity, where this insect occurs.

Diagnosis. Lanka sahyadriensis , even though similar to L. ramakrishnai in the structure of the aedeagus as well as most external features, has a wider body length-width ratio, slightly longer antennae and finer elytral punctures than L. ramakrishnai . The aedeagus in ventral view is distinctly narrowed preapically in L. sahyadriensis compared to L. ramakrishnai . Intercoxal ridges on first abdominal ventrite nearly extend the full length of the segment in L. ramakrishnai where as in L. sahyadriensis they only reach half of its length. L. ramakrishnai can be readily distinguished from L. sahyadriensis by the color of its elytra, the length of intercoxal ridges on the first abdominal ventrite, structure of the spermatheca and vaginal palpi. L. aruna with larger size, red dorsum and distinct male and female genitalia can readily be separated from L. ramakrishnai .

Remarks. Lanka sp. reported by Premkumar and Nair (1987) as a pest of black pepper in Kerala is L. sahyadriensis . This was confirmed by the examination of a specimen (with the label CIE A 12026 , here designated as paratype, to be deposited in PNC) identified by M. L. Cox as Lanka sp. in the Indian Institute of Spices Research, Calicut, where Premkumar had worked on pollu beetle.

Lanka ramakrishnai occurs abundantly in the plains of Kerala and does considerable damage to black pepper at altitudes below 300 m. But no damage was reported earlier due to this pest in the pepper plantations at altitudes above 900m ( Premkumar, 1980). However, stray infestations of pollu beetle were noticed later in Wayanad and Idukki districts in Kerala and in the Kodagu district in Karnataka above 900m ( Devasahayam, 1992). But L. sahyadriensis has so far been collected only at elevations above 800 m and its most preferred host plant is P. mullesua , which occurs above 1300 m ( Gamble, 1921; Saldanha, 1984). Host plant selection of L. sahyadriensis and L. ramakrishnai appear to overlap with both of them feeding on P. nigrum at higher altitudes.

Figures

FIGURE 38. Lanka sahyadriensis, ventral view.

FIGURES 39–48. Lanka sahyadriensis. 39. intercoxal ridges on first abdominal ventrite; 40. male last abdominal ventrite; 41. aedeagus of holotype, ventral view; 42. same, lateral view; 43. same, distal opening; 44. tegmen; 45–48. aedeagus, variation in shape.

FIGURES 49–53. Lanka sahyadriensis. 49. vaginal palpi; 50. spermatheca (specimen from Naduvattam); 51. spermatheca (specimen from Karnataka); 52. spermatheca (specimen from Doddabetta Valley); 53. tignum.