Lankaphthona yunnantarsella Ruan, Konstantinov & Prathapan

Ruan, Yongying, Konstantinov, Alexander S., Prathapan, Kaniyarikkal D., Zhang, Mengna & Yang, Xingke, 2019, A review of the genus Lankaphthona Medvedev, 2001, with comments on the modified phallobase and the unique abdominal appendage of L. binotata (Baly) (Coleoptera, Chrysomelidae, Galerucinae, Alticini), ZooKeys 857, pp. 29-58 : 29

6. Lankaphthona yunnantarsella Ruan, Konstantinov & Prathapan sp. nov. Figs 7, 8 A–F

Type Locality.

China: Yunnan (Xishuangbanna).

Etymology.

The name is derived from the type locality and the elongate first metatarsomere of this species.

Distribution.

China: Yunnan.

Diagnosis.

Lankaphthona yunnantarsella Ruan, Konstantinov & Prathapan, sp. nov. is close to L. binotata (Baly) due to the similarity in body color and elytral maculation. However, it can be separated from L. binotata (Baly) by the strongly enlarged eyes, narrow vertex and frons, longer antennae and the absence of abdominal appendage on first abdominal ventrite in male.

Description.

Body pale yellow to yellow; meso- and metasternum and apex of metafemur dark brown dorsally; two brown to black spots with indistinct margin present on each elytron: one situated at middle and other at base on mesal side of humerus. Body oval, slightly elongate in dorsal view, dorsum convex in lateral view. Body larger in female, 1.70-2.10 mm in length, 0.80-1.10 mm in width. Body length to width ratio: 1.85-1.95. Pronotum width to length ratio: 1.65-1.75. Pronotum width at base to width at apex ratio: 1.05-1.10. Elytron length (measured along suture) to width of both ratio: 1.30-1.35. Length of elytron to length of pronotum ratio: 3.15-3.25. Width of elytra at base (measured in middle of humeral calli) to width of pronotum at base ratio: 1.30-1.40.

Vertex without punctures, except 2-3 on each side near supraorbital sulcus. Frontal ridge moderately developed, evenly convex. Sides of frontal ridge without sulci or punctures, oblique. Antennal calli obliquely elongate, sub-triangular, conjoined, well delimited with supracallinal, midfrontal, supraantennal, and suprafrontal sulci. Top of frontal ridge acute, produced between antennal calli. Frontal ridge in lateral view moderately convex. Antennal socket close to eye. Width of frontal ridge to antennal sockets (counting surrounding ridges) ratio 0.50-0.60. Eyes strongly enlarged. Distance between eyes (just above antennal sockets) to transverse diameter of eye in frontal view ratio: 1.50-1.60. Longitudinal diameter of eye to transverse diameter of eye in frontal view ratio: 2.00-2.10. Distance between antennal sockets to transverse diameter of one antennal socket ratio: 0.85-0.95. Labrum with four setiferous pores bearing long setae.

Antennae filiform, rather long, about 0.9 times body length in female and 1.0 times body length in male. Proportions of antennomeres as follows: 13:7:8:9:12:11:15:15:15:14:19. Antennomere 2 robust, shorter than antennomere 3 and 4, following antennomeres slender. Length to width of antennomere 9 ratio: 5.85-5.90. Length to width of antennomere 10 ratio: 3.65-3.70. Length to width of antennomere 11 ratio: 5.50-5.55.

Pronotum more or less rectangular, slightly convex, antebasal transverse impression poorly to well developed. Pronotal punctures shallow and minute, slightly larger near antebasal transverse impression. Diameter of pronotal punctures 3-4 times smaller than distance between them. Pronotal punctures nearly as large as elytral ones. Anterolateral callosity of pronotum well developed, truncate and elongate, facing anterolaterally. Lateral margins of pronotum slightly sinuate, not converging anteriorly, with lateral margin obviously explanate. Pronotal base slightly convex at middle.

Elytral humeral callus moderately developed. Impressions or ridges absent on elytron. Elytral punctures minute, confusedly arranged. Elytra at base wider than pronotum.

Length (not counting trochanter) to maximum width of metafemur ratio: 1.95-2.00. Length to width of metatibia in lateral view ratio: 5.65-5.75. Width of metatibia at base to width at apex in dorsal view ratio: 0.45-0.50. Length of metatibia to length of first metatarsomere ratio: 1.80-1.90. Length of metafemur to metatibia ratio: 1.15-1.25. Length of first metatarsomere to length of second metatarsomere ratio: 2.50-2.55.

Subparallel intercoxal ridges on first abdominal ventrite short, not reaching proximal 1/3 of ventrite. Males without appendage on first abdominal ventrite.

Aedeagus nearly parallel sided in ventral view, with basal part slightly wider; apex tri-lobed, with sulci between middle and lateral lobes (Fig. 7F). Ventral groove present. In lateral view, aedeagus almost straight with base and apex very slightly curved ventrally.

Variability.

The number and position of elytral spots are consistent in all the specimens studied: one situated near middle and the other at the base on mesal side of humerus. However, spots varied from brown to black and poorly visible (e.g., in holotype, Fig. 7A) to distinctly prominent (e.g., in paratype, female, Fig. 8A, B). The basal spot on the mesal side of the humerus is almost invisible in the holotype, but for a trace of brown maculation. In female, an additional longitudinal spot present near lateral margin of elytra, merging with the middle spot.

Type material.

Holotype: ♂ (IZCAS), labels: 1) Yunnan, Xishuangbanna, Menglun, botanical garden, lvshilin, 2009.xi.17, Guo Tang & Zhiyuan Yao leg., 21°54.609'N, 101°17.090'E, 643 m, IZCAS; 2) Holotype, Lankaphthona yunnantarsella sp. nov. Des. Ruan, Konstantinov & Prathapan, 2018.

Paratypes: 2♂ (1 in TARI, 1 to be transferred to USNM), labels: 1) Yunnan, Xishuangbanna, Menglun, botanical garden, lvshilin, 2009.xi.17, Guo Tang & Zhiyuan Yao leg., 21°54.609'N, 101°17.090'E, 643 m, IZCAS; 2) Paratype, Lankaphthona yunnantarsella sp. nov. Des. Ruan, Konstantinov & Prathapan, 2018; 1♂1♀ (IZCAS), labels: 1) Yunnan, Xishuangbanna, Menglun, 2011.viii, 1088 m; 2) Paratype, Lankaphthona yunnantarsella sp. nov. Des. Ruan, Konstantinov & Prathapan, 2018.

Remarks.

The specimens of L. yunnantarsella sp. nov. Ruan, Konstantinov & Prathapan and L. nigronotatus were collected from the same location in Yunnan province, China. Hence it is very easy to confuse these two species due to their similarity in body shape, color and elytral maculation. However, they can be carefully separated based on external characters. In L. yunnantarsella antennae are about 0.9-1.0 times body length, antennomere 2 shorter than antennomere 3 and 4 and each elytron with two dark spots (in males), one situated at middle and the other basally on mesal side of humerus. In L. nigronotatus , antennae are about 0.8 times body length, antennomere 2 longer than antennomere 3 and 4; and elytron with three dark spots: one situated at middle, one elongate spot on sutural margin near apex and the third one at apex.