Demarchus hsui (Coleoptera, Chrysomelidae, Galerucinae, Alticini), a new species from Taiwan, with notes on immatures and biology Author Lee, Chi-Feng https://orcid.org/0000-0003-1996-0557 Applied Zoology Division, Taiwan Agricultural Research Institute, Taichung 413, Taiwan chifeng@tari.gov.tw Author Chen, Jung-Chan No. 16, Lane 75, Shengli East Road, Pingtung City, Pingtung County 900, Taiwan text ZooKeys 2023 2023-08-30 1177 3 21 http://dx.doi.org/10.3897/zookeys.1177.97854 journal article http://dx.doi.org/10.3897/zookeys.1177.97854 1313-2970-1177-3 E867FD681EF149FC8DE7ACC73F837CA8 F898831BDC095D819591A1707E77BEB6 Demarchus hsui sp. nov. Figs 1 , 2 , 3 , 4 , 5 , 6 , 7 Type material. Holotype ♂ (TARI, The Insect Collection, Applied Zoology Division, Taiwan Agricultural Research Institute, Taichung, Taiwan): Taiwan. Hualien: Pilu (碧綠), 20.VI.2022, leg. Y.-F. Hsu. Paratypes: 7♂, 10♀ (3♂, 3♀: BMNH; 4♂, 7♀: TARI), data same as holotype; 4♂, 4♀ (TARI) same locality as holotype, 13.VII.2022, leg. Z.-I. Chen. Additional material examined. Five mature larvae (TARI), same locality as holotype, 20.IX.2022 , leg. Y.-F. Hsu. Description. Adults. Colour (Fig. 1A-C ) reddish brown, head black, but antenna dark brown or black, prothorax pale yellow, legs yellow with outer margins blackish brown. Pronotum transverse, 2.0 x wider than long, disc convex and with lateral fovea, disc with sparse, coarse punctures, lacking antebasal transverse groove; lateral margin rounded, anterior margin slightly concave, posterior margin slightly convex. Elytra slightly wider posteriorly, with shallow transverse impression, widest at apical 1/3, apex convergently rounded, 1.5-1.7 x longer than wide, disc with dense, fine punctures and dense pubescence. Figure 1. Demarchus hsui sp. nov. female A dorsal view B lateral view C ventral view. Male. Length 4.8-5.5 mm, width 2.2-2.5 mm. Antenna filiform (Fig. 2A ), ratio of length of antennomeres I to XI 1.0: 0.5: 0.6: 0.8: 0.8: 0.9: 0.9: 0.8: 0.7: 0.7: 0.9; ratio of length to width of antennomeres I to XI 3.0: 2.4: 3.1: 3.0: 3.2: 3.3: 3.4: 3.6: 3.2: 3.2: 3.9. Aedeagus (Fig. 2C-E ) with apical 1/2 lanceolate, apex narrowly rounded, basally narrowed; strongly curved in lateral view, slightly recurved near base; tectum slightly sclerotised, with median, longitudinal, strongly sclerotised area from basal margin; endophallic sclerites absent. Apex of abdominal ventrite V (Fig. 2I ) with median, angular notch, internally covered by flattened sclerite. 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. Female. Length 5.1-6.0 mm, width 2.4-3.0 mm. Antenna (Fig. 2B ) similar to males, ratio of length of antennomeres I to XI 1.0: 0.5: 0.6: 0.9: 0.9: 0.8: 0.8: 0.7: 0.7: 0.6: 0.9; ratio of length to width of antennomeres III to XI 3.6: 2.6: 2.7: 3.7: 3.6: 3.5: 3.7: 3.4: 3.5: 3.0: 4.5. Ventrite VIII (Fig. 2F ) weakly sclerotised, T-shaped, with dense, short setae along apical margin, apical margin irregular, spiculum short. Spermathecal receptaculum (Fig. 2G ) slightly swollen; pump long and strongly curved, apex widely rounded; spermathecal duct short, shallowly projecting into receptaculum. Gonocoxae (Fig. 2H ) short and widely conjoined at base, each gonocoxa widest at apical 1/3, with dense setae along apical areas. Diagnosis. Adults of this new species are similar to those of D. nigriceps in colour pattern, but differ in possessing black antennae and outer margins of tibiae (Fig. 1A-C ) (yellow antennae and tibiae in D. nigriceps (Fig. 11C, F )), pronotum without antebasal transverse groove (Fig. 1A ) (pronotum with antebasal transverse groove in D. nigriceps (Fig. 11C )), elytra with transverse impression (Fig. 1A ) (elytra without transverse impression in D. nigriceps (Fig. 11C )), antennomeres IV-VII subequal in length and longer than antennomere III (IV-VII subequal in length and shorter than antennomere III in D. nigriceps ), antennomeres VIII-X subequal in length and shorter than antennomere XI (antennomere VIII-XI subequal in length in D. nigriceps ). Mature larvae. Length 9.5-9.6 mm, width 2.5-2.6 mm. Live specimens (Fig. 7E ): body form elongate, flattened; pale yellow, head and legs blackish brown; prothoracic and abdominal tergite IX with large sclerotised patches; thoracic tergites with small, longitudinal, curved sclerotised patches at sides; thoracic ventrites with small rounded sclerotised patches medially; lateral margins of meso- and metathoracic, and abdominal segments I-VIII expanding outwards, abdominal segments I-VIII each bearing one small process at lateral margins. body bearing tiny setae, the latter sometimes reduced to pores. Spiracles present on mesothorax and abdominal segments I-VIII (Fig. 3A ). Figure 3. Demarchus hsui sp. nov. mature larva. A dorsal view. B pro-mesothorax, dorsal view C abdominal segment I, dorsal view D pro-mesothorax, ventral view E abdominal segment I, ventral view. Abbreviations: Co-Coxa; Sp-spiracle; Tn-Trochantin. Head (Fig. 4A ). Flattened, narrower than prothorax, partly retracted into prothorax; frontal sutures (Frs) V-shaped, epicranial suture (Eps) short; endocarina (En) wide. Stemmata absent. Epicranium (Ep): with six pairs of short setae (e1-7) and nine pairs of pores (p1-9); e4-6 situated at posterolateral part of epicranial halves. Frons (Fr): with three pairs of short setae (f1-3) and one pair of pores. Clypeus (Cly): transverse, with three pairs of tiny setae near base. Clypeus and frons devided by apistomal sulcus. Labrum (Lbr): transverse, with one pair of short setae near midline; apical edge rounded. Epipharynx (Fig. 4E ): densely setose anteriorly; with four or five large setae on each side; sensilla arranged in one pair of transverse rows. Mandibles (Fig. 4D ): symmetrical, palmate, each mandible with four sharp teeth, without penicillus. Antennae (Fig. 4C ): weakly sclerotised, two segmented, attached to membranous area at end of frontal suture; first antennomere partly membranous, bearing one small conical sensory papilla and several sensilla; second antennomere small, without sensilla. Maxilla (Fig. 4B ): Stipes (St) elongate, bearing one pair of long setae and two pairs of short setae near lateral margin; with a long, curved sclerotisation (Scl). Mala with galea (Gal) and lacinia (Lac) not fused; galea wide, bearing six stout setae and numerous hair-like setae at apex; apical part of lacinia with dense hair-like setae; maxillary palpus (Mxp) three-segmented, second palpomere bearing two setae, one and third palpomeres each bearing one sensilla. Labium (Fig. 4B ): submentum (Smen) trapezoid, bearing two pairs of long setae at sides; mentum not well defined; prementum short and transparent, with horseshoe-shaped mental sclerite (Mens), bearing one pair of setae at base; ligula (Lig) membranous, not separated from prementum, anterior edge broadly concave, bearing numerous hair-like setae; labial palpi (Lbip) small, two segmented; with three pairs of sensilla near labial palpi. Figure 4. Demarchus hsui sp. nov. mature larva A head B maxilla and labium C antenna D mandible E epipharynx F middle leg G abdominal segment IX, dorsal view. Abbreviations: Cly-clypeus; Co-coxa; e1-e6-epicranial setae; En-endocarina; Ep-epicranium; Eps-epicranial suture; f1-f3-frontal setae; Fe-femur; Fr-frons; Frs-frontal suture; Gal-galea; Lac-lacinia; Lbip- labial palpus; Lig-ligula; Mens-mental sclerite; Mxp-maxillary palpus; p1-p9-epicranial pores; Pu-pulvillus; Scl-sclerotisation; Senp-sensory papilla; St-stipes; Ti-tibia; Tn-trochantin; Tr-trochanter. Thorax. Prothorax: dorsum (Fig. 3B ) with one pair of pores and two pairs of short setae at basal areas of sclerotised patches; two pairs of short setae near base halfway between sclerotised patches and bases of lateral process; three pairs of short setae at sides. Sternal region (Fig. 3D ) with one small, sclerotised patch medially, two pairs of short setae at anterior and posterior parts of sclerotised patch respectively. Mesothorax: dorsal region (Fig. 3B ) with pores and short setae arranged into two transverse rows, anterior row with two pairs of pores and one pair of setae, posterior row with four setae; lateral longitudinal, sclerotised patches bearing three short setae. Sternal region (Fig. 3D ) with one very small, sclerotised patch, one pair of short setae and one pair of pores at anterior and posterior parts outside sclerotised patch. Metathorax: same pattern as mesothorax, except for absence of spiracle. Legs (Fig. 4F ): five segments; trochantin (Tn) triangular, without setae or pores; coxa (Co) transverse, bearing several pores at basal half, and two short setae near apical margin; trochanter (Tr) triangular, lacking setae but with several pores; femur (Fe) small, with one long seta on mesal margin, and one small setae at inner face; tibia (Ti) enlarged at base decreasing toward apex, bearing seven short setae at apical 1/2; tarsungulus sclerotised, falciform, bearing one basal setae; pulvillus (Pu) bladder-like, as long as tarsungulus. Abdomen. Segments I-VIII: dorsal region (Fig. 3C ) lacking setae, pores arranged into two transverse rows, bearing three pairs of pores at anterior and posterior row respectively, and three pairs of pores on lateral process; sternal region (Fig. 3E ) with pores arranged into three transverse rows, one pair of pores in anterior row, four pairs of pores in middle row, and two pairs of pores in posterior row, three pairs of pores on lateral process. Segment IX (Fig. 4G ): pygidium moderately sclerotised; disc with pores arranged into two transverse rows, three pairs of pores in anterior and posterior rows respectively; three pairs of short setae along lateral margin. Host plant. Loranthaceae : Taxillus rhododendricolus (Hayata) S.T. Chiu. Biology. Larvae are leaf miners of Taxillus rhododendricolus , which is a hemiparasite. More than 20 larvae (Fig. 5C-E ) were collected from branches (Fig. 5A, B ) cut from the host tree, Salix fulvopubescens Hayata var. fulvopubescens Hayata (褐毛柳) at a height of approximately six meters during late August 2020. Forest type is mixed coniferous, including Picea asperata Mast., Tsuga chinensis (Franch.) Pritzel ex Diels., and Cunninghamia konishii Hayata, with some evergreen broad-leaved and deciduous trees. During 2022, 18 adults were collected using sweep nets from the same plant on June 20 by Dr. Hsu (see types). Eight additional adults were collected from the host plant on trees of Carpinus rankanensis Hayata on July 13. Some other collecting trips were carried out during different months. These collecting events indicated that adults appear during June and July, egg masses during early August, and larvae only during late August and September, no life stages were found after October, and it is clear that D. hsui sp. nov. is an univoltine species. By contrast, populations of D. pubipennis in Pakistan are multivoltine, with up to four generations a year ( Mushtaque and Baloch 1979 ). Figure 5. Field photographs taken from the type locality, Pilu (碧綠) A host plant, Taxillus rhododendricolus (indicated by arrows) B close-up and another angle of T. rhododendricolus C branch of T. rhododendricolus with egg masses (indicated by black arrows) and larvae (indicated by red arrows) D branch of T. rhododendricolus with young larvae (indicated by arrows) mining leaves E branch of T. rhododendricolus with older and younger larvae (indicated by red arrows) mining leaves F branch of T. rhododendricolus with egg masses (indicated by black arrows). Egg masses were deposited at some distance from each other on undersides of leaves (Fig. 6A ). Females scratched the leaf surface several times (Fig. 6B ) so that neonate larvae could burrow into the leaves easily. Then four or five eggs (Fig. 6C ) were laid and covered by faeces. Usually only one larva hatched successfully from each egg mass (Fig. 6D ) and began mining leaves. Figure 6. Egg masses of Demarchus hsui sp. nov. A typical distribution of egg masses of Demarchus hsui sp. nov. on underside of leaf B egg mass removed from point where it was deposited, scratch marks indicated by arrows C egg mass from a different angle with eggs exposed (indicated by arrow) D backlit image with tunnels constructed by the new hatched larvae indicated by arrows. Leaves of T. rhododendricolus decayed as soon as larvae constructed tunnels (Fig. 7A ). Tunnels made by larvae were always transverse and turned towards the leaf apex (Fig. 7B, C ). Larvae turned tunnels basally when conditions were not suitable to maintain the apical direction. Such a feeding pattern caused the entire leaf to decay from apex to base (Figs 5D, E , 6D , 7B ). Larvae exited tunnels when conditions deteriorated and searched for more suitable leaves. They were able to tunnel into newly selected leaves and continue development (Fig. 7D ). Mature larvae (Fig. 7E ) emerged from tunnels and walked or fell to the ground, mainly falling when disturbed. They burrowed into soil and built underground chambers for pupation. Figure 7. Larvae and adult of Demarchus hsui sp. nov. A young larva (indicated by arrow) mining leaf B larval tunnels and feeding marks made by adults on leaf (indicated by arrows) C diagrammatic illustration of larval tunnels for Fig. 9B D older larva starting to mine leaf E mature larva that emerged from larval tunnel F adult feeding on leaf. Adults on leaves of T. rhododendricolus were active during the day (Fig. 7F ). They fed on the upper surface of leaves, leaving round feeding scars (Fig. 7B, E ). Remarks. Larvae of D. hsui sp. nov. exhibit unusual characters that are typical for leaf miners ( Takizawa 2005 ), including flattened body and head, head with vertex incised in a U- or V-shape posteriorly, and body surface without setae or tubercles. Etymology. This new species is named for Dr. Yu-Feng Hsu (徐堉峰), who is a well-known butterfly expert and the first person to collect specimens. Distribution. The new species is only recorded from the type locality -- Pilu (碧綠), in Hualien County, East Taiwan. It is located at 24°10'51.3"N , 121°24'11.6"E , 2150 m MSL, and protected by the Taroko National Park (太魯閣國家公園). This locality seems to be the biodiversity hotspot. The rarely collected chrysomeline Ambrostoma chinkinyui Kimoto & Osawa, 1995 is also only known from this locality ( Kimoto and Osawa 1995 ), as well as multiple undescribed species (unpublished data).