Lanka Maulik

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 : 2-5

publication ID	https://doi.org/ 10.11646/zootaxa.1681.1.1
persistent identifier	https://treatment.plazi.org/id/727987BB-FFB6-D31F-FF11-F0E0FE1EFC8B
treatment provided by	Felipe
scientific name	Lanka Maulik
status

Treatment

Genus Lanka Maulik

( Figs 1–35 View FIGURE 1 View FIGURES 4–12 View FIGURE 13 View FIGURES 14–18 View FIGURES 19–26 View FIGURES 27–35 , 38–56 View FIGURE 38 View FIGURES 39–48 View FIGURES 49–53 )

Lanka Maulik, 1926: 284 , 304 (type species L. brunnea Maulik, 1926 , Sri Lanka , by original designation). ― Chen, 1936: 630. ― Heikertinger & Csiki in Junk, 1940: 528. ― Samuelson, 1969: 34. ― Scherer, 1969: 5, 14, 233. ― Seeno & Wilcox, 1982: 145. ― Kimoto & Takizawa, 1994: 46, 70, 243, 337, 398, 412, 502. ― Kimoto & Chu, 1996: 110–111. ― Kimoto & Takizawa, 1997: 248, 326, 409. ― Kimoto, 2000: 109, 205–206, 297.

Horaia Chûjo, 1935: 357 View in CoL (type species H. nigra Chûjo, 1937 , Taiwan, by original designation). ― 1937: 57. ― Chûjo & Ohno, 1961: 1, 2. ― Heikertinger & Csiki in Junk, 1940: 528. ― Kimoto, 1965: 403; 1966: 615. ― Samuelson, 1967: 141. ― Seeno & Wilcox, 1982: 145. ― Kimoto & Takizawa, 1994: 337 (synonymised). ― Konstantinov & Vandenberg, 1996: 271, 320–322.

Dentisterna Medvedev, 1993: 53 (type species D. bicolor Medvedev, 1993 , Mindanao, by original designation). ― Konstantinov & Vandenberg, 1996: 320 (synonymised).

Distribution. India, Sri Lanka , Thailand, China, Taiwan, Japan, the Philippines and the Solomon Islands.

Host plants. Piper spp. (Piperaceae) and Magnolia sp. (Magnoliaceae) ( Chûjo & Ohno, 1961).

Diagnosis. Length 2–4 mm. Vertex unusually convex. Orbit and interantennal space narrow. Orbital sulcus deep, wide, close to eye, reaching posterior margin of eye. Antennal calli unusual, distinctly depressed, separated from each other by frontal ridge, oblique, anterior end partially entering into interantennal space. Frontal ridge narrow, sharply raised, proximally joining vertex. Anterofrontal ridge triangular, flat anteriorly. Labrum with a row of four setiferous pores. Maxillary palp with penultimate palpomere incrassate. Pronotum without impressions, posterior margin bisinuate. Anterior coxal cavities open behind. Elytral punctures shallow, forming regular to semiregular striae. Metasternum with posterior margin bisinuate, raised on either side of middle forming a pair of protuberances distally. Metatibia characteristically curved, with ends towards lateral sides in dorsal view, dorsally flat and distinctly margined on either side. First metatarsomere slightly longer than half of metatibia, tarsal articulation on well developed callosity visible in lateral view. First abdominal ventrite medially with a pair of subparallel ridges joining anteriorly. Spermatheca with long coiled duct. Vaginal palpi appear separate in dissections, without anterior or posterior sclerotization.

Description. Body of medium size, length 2–4 mm, broadly oblong, moderately convex in lateral view ( Figs 13 View FIGURE 13 , 36). Color non-metallic yellow, brown, red or black.

Head unusual being distinctly depressed between eye and vertex, hypognathous, not exerted. Vertex convex, much raised above depressed portion posterior to eye as well as antennal callus ( Fig. 14 View FIGURES 14–18 ). In lateral view, line formed by frons and vertex concave to straight in middle. Supraorbital pore situated between lateral edge of vertex and orbital sulcus, with a brightly colored, shiny, moniliform tubercle bearing a short upcurved seta, with minute setiferous pores anterolaterally. Midcranial suture absent. Supracallinal sulcus distinct, shallow, curved, obscured by anterior edge of vertex. Midfrontal and suprafrontal sulci absent as frontal ridge joins vertex. Supraantennal sulcus weakly developed. Supraorbital sulcus wider and deeper than supracallinal and supraantennal sulci. Orbital sulcus deep, wide, close to eye, reaching posterior margin of eye. Orbit narrow, slightly wider than half of transverse diameter of antennal socket. Eye moderately large, vertical diameter more than horizontal, inner margins subparallel, indistinctly concave near antennal socket. Subgenal suture distinct. Distance between eyes 3.3–4.0 times diameter of one antennal socket. Distance between antennal sockets 0.8–1.3 times wider than transverse diameter of one antennal socket. Transverse diameter of one antennal socket 1.6–4.0 times distance between eye and adjacent socket. Distance between antennal sockets 2.2–4.0 times distance between adjacent antennal socket and eye. Antennal callus unusual, distinctly depressed, oblique, spindle shaped, anteromedial end partially entering into interantennal space, posterior margin distinctly depressed compared to adjacent margin of vertex; vertex, frontal ridge much raised compared to antennal calli. Frontal ridge moderately long, proximally joins vertex, extremely narrow, raised like a sharp blade between antennal sockets. Anterofrontal ridge triangular, flat anteriorly, laterally raised. Frontoclypeal suture with a row of short as well as long setae. Labrum with transverse row of four setiferous pores besides a pair of tiny sensilla each placed lateral to middle pair of setiferous pores ( Fig. 15 View FIGURES 14–18 ); apical margin concave with seven sensilla on each side in L. ramakrishnai and L. sahyadriensis ; torma long; externally visible part of labrum about two times wider than long. Mandible palmate with five denticles ( Fig. 16 View FIGURES 14–18 ). Maxilla in L. ramakrishnai with lacinia wider than galea, cardo slightly longer than stipes ( Fig. 17 View FIGURES 14–18 ). Maxillary palp with palpomeres 2–4 subequal in length; third incrassate, about as wide as long; fourth conical, pointed; sensilla patch of last maxillary palpomere wider than long with about 10–12 embedded sensilla in L. ramakrishnai as well as L. sahyadriensis . Labium in L. ramakrishnai with three palpomeres per palpus, second longest, prementum with a pair of long setae in middle ( Fig. 18 View FIGURES 14–18 ). Antenna 11 segmented, filiform, reaches proximal 1/3 to beyond middle of elytron. First antennomere thick, slightly shorter than two times length of second; second slightly thinner than first; third slender, subequal to first or slightly longer; last asymmetrical.

Pronotum 1.4–1.6 times wider than long, convex, without antebasal transverse impression, disc with minute as well as small punctures, anterior margin straight, posterior margin bisinuate; lateral margin curved, widest in middle. Anterolateral callosity convex to slightly concave, anteriorly higher than posteriorly, seta bearing pore on dorsal posterior face, nearly as long as 1/3 of lateral margin including anterolateral callosity. Posterolateral callosity longer than width of lateral margin, seta bearing pore on lateral face. Seta on both anterolateral and posterolateral callosities separately as long as lateral margin including anterolateral callosity. Anterior coxal cavities open behind. Prosternum 1.5–3.6 times longer than width of intercoxal prosternal process, length of prosternum 3.0–9.4 times distance between anterior margin of prosternum to procoxal cavity. Intercoxal prosternal process extending beyond procoxa, convexly arched in lateral view, slightly narrowed in middle with characteristic depression posteriorly, rest of top nearly flat, posteriorly widened, apical margin convex ( Fig. 21 View FIGURES 19–26 ). Proendosternites in L. ramakrishnai as well as L. sahyadriensis relatively short, transverseoblique, top bluntly angulate ( Fig. 23 View FIGURES 19–26 ). Mesoscutum with well developed internal ridges, mesoscutellum flat with narrowly rounded apex ( Fig. 19 View FIGURES 19–26 ). Mesosternum with raised lateral margin, depressed on top, posterior margin concave ( Fig. 22 View FIGURES 19–26 ). Mesosternum 0.6–1.2 times longer than width of intercoxal part, length of mesosternum 1.3–2.7 times distance between anterior margin of mesosternum to mesocoxal cavity. Mesendosternite in L. ramakrishnai as well as L. sahyadriensis slightly narrowed at base, rectangular in middle, narrowing apically, not connecting with mesepisternomeral ridge ( Fig. 24 View FIGURES 19–26 ). Metanotum fully developed with allocrista as long as medial groove in L. ramakrishnai and L. sahyadriensis ( Fig.20 View FIGURES 19–26 ). Metasternum with posterior margin bisinuate, raised on either side of middle forming a pair of distinct protuberances distally, much raised above level of first abdominal sternite; anterior margin arched, sharply raised ( Fig. 22 View FIGURES 19–26 ). Metasternum 1.3–2.4 times longer than prosternum. Metendosternite in L. ramakrishnai and L. sahyadriensis with stalk slightly shorter than wide, arms with fully developed ridges, tendons of meso-metafurcal muscles poorly developed ( Fig. 25 View FIGURES 19–26 ).

Elytron with sides convex, humeral callus well developed with weak depression posteriorly, apex convex forming obtuse angle with sutural margin. Epipleuron nearly horizontal, extends beyond 4/5, not reaching apex, maximum width of epipleuron subequal to or slightly less than that of mesofemur; width of mesocoxal cavity about 1.5–2.0 times width of epipleuron. Ventral surface of elytron with three patches of sensilla in L. ramakrishnai and L. sahyadriensis : anterior as well as middle sensilla patch near lateral margin; anterior sensilla patch nearly circular; middle oblong, longer than anterior patch; third near posterior end of sutural margin, narrow, oblong; apex with sensilla stripe. Elytral punctures shallow, small, larger than those on pronotum, forming regular to semiregular striae, indistinct posteriorly, each puncture with a microseta visible under high power, interstices flat, minutely punctured. Hind wings well developed, venation complete ( Fig. 26 View FIGURES 19–26 ).

Pro- and mesotibiae without apical spine. Forefemur slightly shorter than or subequal to foretibia. Mesofemur shorter than mesotibia. Foretibia gradually widening from base to apex, dorsal surface convex. First protarsomere slightly wider in male than in female, ventrally flat, ventral side without setae in male. Second protarsomere narrower than first, as short as half of first. Third protarsomere shorter than first, slightly longer than second, bilobed, with feather shaped setae arranged in transverse semiregular rows ventrally. Last protarsomere about two times as long as third, claw shorter than half of claw tarsomere; appendix of claw broader than long, with an incision between claw and appendix. Metafemora greatly incrassate with maximum width at proximal 1/3 to 1/4. Metatibia characteristically curved, with ends towards lateral sides in dorsal view; gradually widening from proximal end to distal end, dorsal surface smooth, without setae, more or less flat, distinctly margined on either side; lateral margin of dorsal surface of metatibia with a regular row of thick bristles in about distal 1/2 to 2/5, mesal margin with such bristles in about distal 1/5; tarsal articulation on well developed callosity visible in lateral view; proximal to tarsal articulation a circular concavity with a broad, flat, triangular denticle on each side. Metatibial spine about as long as claw or slightly longer, thicker than claw; articulated at middle of apex. First metatarsomere slightly longer than half of metatibia as well as other tarsomeres combined, straight in lateral view, gradually widening from proximal end to distal end; ventral side densely setose, setae being hair like, different from those on dorsal side. Second metatarsomere as long as half of first or slightly shorter. Third metatarsomere about half as long as second or slightly longer. Ventral side of second metatarsomere with hair like setae, ventral side of third metatarsomere with feather like setae.

First abdominal ventrite slightly longer than next three combined, medially with a pair of characteristic, subparallel ridges joining anteriorly in intercoxal region and inverted U-shaped ( Figs 4 View FIGURES 4–12 , 27 View FIGURES 27–35 , 38 View FIGURE 38 , 39 View FIGURES 39–48 ). Third and fourth abdominal ventrites together equal to or shorter than fifth. Posterior margin of last visible abdominal ventrite in male bisinuate or nearly so with a distinct lobe in middle, entire in female ( Figs 5 View FIGURES 4–12 , 28 View FIGURES 27–35 , 40 View FIGURES 39–48 ). Last visible tergite of female 1.3–1.7 times wider than long, with a deep, incomplete median longitudinal groove not reaching distal margin.

Spermatheca with distinct pump, receptacle and duct; pump with horizontal part longer than vertical; receptacle 2.5–3.5 times longer than wide, narrowed towards duct; duct forms obtuse to acute angle with receptacle, longer than receptacle, highly coiled or folded, distal end pointed towards receptacle. Vaginal palpi unique, weakly connected or appear separate in dissections, lacks distinct anterior or posterior sclerotization, with setae near apex slightly shorter than two times maximum width of a palpus, lateral and medial margins do not form angle at apex. Tignum channeled along middle, anteriorly widened, flat, posterior membranous area wider than long with a row of fine setae along posterior margin. Median lobe of aedeagus with proximal end deeply cleft in ventral view, ventral surface convex, depressed preapically; in lateral view moderately curved with acutely narrowed, more or less recurved apex; distal opening partially covered by membrane with two or three sclerotized laminae (Figs 2, 3, 6–8, 29–31, 41–48). Tegmen with stem longer than or subequal to arm ( Figs 9 View FIGURES 4–12 , 32 View FIGURES 27–35 , 44 View FIGURES 39–48 ).

Sexual dimorphism. The posterior margin of last visible abdominal ventrite (S VII) in male is bisinuate (see Figs 5 View FIGURES 4–12 , 28 View FIGURES 27–35 & 40 View FIGURES 39–48 ) with a distinct lobe in middle but is entire in female. The first protarsomere is slightly wider in male than in female. In some cases, first mesotarsomere is also similarly widened. But this character is unreliable for differentiating sexes, as it is variable and difficult to make out. The ventral side of first protarsomere in male lacks seta but has at least minute setae in female.

Remarks. Lanka belongs to a group of genera with a pair of subparallel ridges along the middle of first abdominal ventrite and characteristically curved metatibia with flat dorsal surface. This unique group, probably monophyletic, is represented in the Indian subcontinent by Bikasha Maulik , Lankaphthona Medvedev , Philogeus Jacoby and Tegyrius Jacoby besides Lanka . All other Oriental flea beetle genera can be separated from Lanka by the structure of the head. Depressed antennal calli, and the sharply raised frontal ridge, which is extremely narrow between antennal sockets, joining vertex proximally, are the salient features of Lanka . Another interesting feature of Lanka is the vaginal palpus that lacks distinct anterior or posterior sclerotization. Lanka closely resembles Philogeus , but the antennal callus in Philogeus is indistinct and its posterior margin is not distinctly depressed compared to adjacent margin of vertex while the posterior margin of antennal callus in Lanka is distinctly depressed imparting a completely sunken appearance. Philogeus has a well developed antebasal transverse impression on the prothorax that Lanka lacks. All the species of Indian Lanka have a convoluted, long spermathecal duct while at least three undescribed species of Philogeus from India that were studied, possess a short, uncoiled spermathecal duct. In India and Sri Lanka , the species of Lanka feed on Piper spp. (Piperaceae) , whereas Philogeus feeds on Menispermaceae plants. Tegyrius , also Piperaceae feeder, resembles Lanka in several respects. But Tegyrius can be separated from Lanka based on the structure of the head and female genitalia. The frontal ridge in Tegyrius is wider than in Lanka and is separated from vertex by antennal calli and does not join vertex proximally (frontal ridge proximally joins vertex in Lanka separating antennal calli). Midfrontal sulcus is well developed in Tegyrius but is absent in Lanka . Unlike in Lanka , the antennal calli are not depressed but are as high as the vertex in Tegyrius . The vaginal palpus has distinct anterior and posterior sclerotizations in Tegyrius that are absent in Lanka . Frontal ridge in Bikasha is narrowed anteriorly, but widened anteriorly in all the above mentioned genera. In Bikasha , the anterofrontal ridge is poorly developed and is flat. In all other genera of the group the anterofrontal ridge is triangular and forms a laterally raised ridge. Midfrontal and suprafrontal sulci are well developed in Bikasha while they are absent in Lanka . Lankaphthona and Bikasha are distinct from other genera of the group in having six setiferous pores on the labrum. Lankaphthona is similar to Philogeus in having the sulci delimiting the antennal calli indistinct. These genera can be separated by the key given below.

This study bridges the gap in earlier known distribution of species of Lanka between Philippines and Sri Lanka in the Oriental Region. All Indian species of Lanka can be differentiated from the type species L. brunnea Maulik from Sri Lanka , (the holotype, ( Fig.1 View FIGURE 1 ) which was examined), by the black head and pronotum (head and pronotum either yellowish brown, light brown or red in Indian Lanka ) and the structure of the aedeagus (Figs 2, 3) which is greatly broadened preapically in ventral view (aedeagus is narrowed preapically in Indian species in ventral view). Specimens from Udawattekele Sanctuary in Sri Lanka identified as L. brunnea by Kimoto (2003) were also examined, and they belong to a species of Tegyrius similar to L. brunnea in coloring and lacking the antebasal transverse impression. Holotype of Lanka octogona (Bechynè) was examined. Antennal calli are contiguous and not depressed in this species. L. octogona is not included in the key as this is unlikely to be a member of Lanka . The specimen from Kandy in Sri Lanka named as L. brunnea by Bechynè (1954) on examination was found to be misidentified.