Demarchus Jacoby, 1887

Lee, Chi-Feng & Chen, Jung-Chan, 2023, Demarchus hsui (Coleoptera, Chrysomelidae, Galerucinae, Alticini), a new species from Taiwan, with notes on immatures and biology, ZooKeys 1177, pp. 3-21 : 3

Demarchus Jacoby, 1887

Demarchus Jacoby, 1887: 101 (type species: Demarchus pubipennis Jacoby, 1887, by original designation); Maulik 1926: 135 (redescription); Scherer 1969: 196 (catalogue).

Included species.

Demarchus pubipennis Jacoby, 1887, D. javanus Bryant, 1941, D. nigriceps Chen & Wang, 1988, D. hsui sp. nov.

Redescription.

Body elongate rounded, head visible from above. Head (Fig. 8A ) drawn into prothorax, hypognathous, broadly oval in frontal view; vertex large, covered with dense, coarse punctures and short setae; antennal calli rectangular, well separated from vertex by deep furrow, not separated from antennal sockets; antennal sockets large, distance between sockets smaller than diameter of socket, sockets separated by frontal ridge, not separated from eyes; frontal ridge triangular, anterior surface of frons convex, bearing short setae at the sides of frontal ridge; frontal area, including mouth region, not separated from genae; eyes small, convex, the longest diameter of eye smaller than the distance between eyes, not delineated by sulci from vertex and frons. Antenna (Fig. 2A, B ) 11-segmented, filiform, long, extending beyond middle of body; antennomere I shorter than two following antennomeres combined. Labrum with two pairs of setae.

Prothorax. Pronotum distinctly wider than long, disc glabrous, with antebasal transverse impression, limited laterally by short longitudinal furrows; hypomera (hyp) (Fig. 8B ) large, hypomeral sutures reduced; prosternum above procoxal cavities narrow, narrower than width of procoxal cavities, intercoxal prosternal process (ipp) narrow, its anterior edge straight; procoxal cavities (prc) closed, transversely elongate.

Mesothorax. Mesonotum (Fig. 8C ) of typical shape, lightly sclerotised, prealar projection (pp) well developed, elongate; postmedial projections (pmp) reduced; scutum (scm) widely rounded. Mesoventrite short, mesanepimera and mesaepisterna narrow.

Metathorax. Metanotum (Fig. 8D ) well sclerotised, well developed, and typical for alticines; prescutum (psc) and postnotum (pn) wide. Metaventrite as wide as first abdominal segment, metaventral process reduced, posterior edge of metaventrite medially with deep incision, metaepisterna of typical shape, narrow. Metendosternite (Fig. 8E ) with branches of anterior part of ventral process (avp) well developed, short; furcal arm (fa) narrow and well sclerotised; stalk (s) wide and short.

Elytra elongate oval. Humeral callus well developed. Elytral punctures and pubescence dense and confused. Epipleuron (Fig. 9A, B ) wide, horizontal, and recurved at apical 1/3, and then vertical, almost reaching elytral apex. Elytral binding patch covered with numerous teeth that are rounded in shape, ventral surface of elytra glabrous.

Hind wings. Wing venation (Fig. 9C ) typical for alticines (Konstantinov and Vanderberg 1996), with completely developed wings and no tendency to reduction. Typical set of veins is present; radius (r), sector of radial vein (rt), medial veins 1 (m1) and 2 (m2), cubital vein 1b (cu1b), and precubital vein (pcu). In addition, first jugal vein (j1) is also visible.

Abdomen. Ventrites short, wide, without projections or convexities, ventrite I shorter than metasternum; sexual dimorphism present in the shape of ventrite V (apical margin with median notch in males but absent in females); pygidium without medial longitudinal groove; tergite VIII well-developed.

Male genitalia (Figs 2C-E , 10A, B ) consisting of median lobe of aedeagus, and Y-shaped tegmen. Aedeagus lacking endophallic spiculae.

Female genitalia consisting of ventrite VIII, gonocoxae, and spermatheca. Ventrite VIII (Figs 2F , 10C ) T-shaped, base well-sclerotised, speculum short, slightly longer than wide, its apical margin with dense setae. Spermathecal receptacle (Figs 2G , 10D ) slightly swollen, sclerotised spermathecal duct very short, pump long, and strongly curved. Gonocoxae (Figs 2H , 10F ) short and wide, basally joined, with dense setae at apical areas.

Legs. Anterior and middle legs of typical shape, without modifications; tibiae without apical spurs, furrows, grooves, ridges, or excavations. Posterior femora slightly swollen; posterior tibiae comparatively short, not longer than length of femora; metafemoral spring simplified (Fig. 9C ), lightly sclerotised, dorsal edge of dorsal lobe (dl) flat, extended arm (ea) of dorsal lobe relative long, ventral lobe (vl) cylindrical, apically rounded, without lower part curving dorsally, and no basal angle, ventral edge of ventral lobe recurved; posterior tarsus attached to tibia apically; tarsus slightly longer than half of tibia; metatarsomere I shorter than three following tarsomeres combined, ventrally with short, dense setae. Tarsomeres III bilobed; tarsal claws bifid.

Remarks.

One character misjudged by Jacoby (1887) and Maulik (1926) is the closed procoxal cavities. Since the posterior margins of the procoxal cavities are so slender, both authors regarded it as the open. In fact, the posterior margins of the procoxal cavities are not reduced in the type specimens of D. hsui sp. nov. and the holotype of D. pubipennis .

Demarchus is easily recognised by the following combination of characters: pubescent elytra, glabrous pronotum, closed procoxal cavities, and unique shape of elytral epipleura, typical form of the Pyrrhalta-like Morpho-Group which, was defined by Furth and Suzuki (1998) based on the metafemoral spring.

Biology.

Immature stages and biology for Demarchus pubipennis , reported by Mushtaque and Baloch (1979), occur on Loranthaceae and larvae are leaf miners. Assertions by Odak et al. (1969) are not supported because the host plant, Cajanus cajan L., belongs to the Fabaceae . Larvae and adults of D. pubipennis did not feed on this plant when tested by Mushtaque and Baloch (1979). Moreover, Odak et al. (1969) indicated that the larvae were root feeders, which is incorrect since they possess morphological characters that are typical of leaf miners, and this lifestyle has been confirmed through field and laboratory observations. The current study confirms that adults of D. hsui sp. nov. feed on leaves of another species of Loranthaceae , Taxillus rhododendricolus , and their larvae are also leaf miners.

Distribution.

Sri Lanka, India, Pakistan, China (Xizang), Indonesia (Java), Taiwan.

Figures

Figure 2. Demarchus hsui sp. nov. adult A antenna, male B antenna, female C apex of aedeagus, front view D base of aedeagus, dorsal view E aedeagus, lateral view F abdominal ventrite VIII, female G spermatheca H gonocoxae I abdominal ventrite V, male.

Figure 8. Diagnostic features of adults of Demarchus hsui sp. nov. A head B ventral view of prothorax C mesonotum D metanotum E metendosternite. Abbreviations: anc-antennal calli; ans-antennal socket; avp-anterior part of ventral projection; e-eye; fa-furcal arm; frr-frontal ridge; hyp-hypomera; ipp-intercoxal prosternal process; lbr-labrum; pmp-postmedial projection; pn-postnotum; pp-prealar projection; prc-procoxal cavity; psc-prescutum; s-stalk; scm-scutum.

Figure 9. Diagnostic features of adults of Demarchus hsui sp. nov. A elytron, ventral view B metafemora spring C base of elytra, lateral view D hind wing. Abbreviations: cu-cubital vein; dl-dorsal lobe; ea-extended arm; j-jugal vein; m-medial vein; r-radial vein; re-recurved part of epipleuron; rt-sector of radial vein; vl-ventral lobe.

Figure 10. Demarchus pubipennis Jacoby, adult A aedeagus, dorsal view B aedeagus, lateral view C abdominal ventrite VIII, female D spermatheca E abdominal ventrite V, male F gonocoxae.