Rhagophthalmus giallolateralus Ho

Ho, Jen-Zon, Chen, Young-Fa, Cheng, Su-Han, Tsai, Xi-Lian & Yang, Ping-Shin, 2012, Two new species of Rhagophthalmus Motschulsky (Coleoptera: Rhagophthalmidae) from Matzu Archipelago, Taiwan with biological commentary, Zootaxa 3274, pp. 1-13 : 9-13

Rhagophthalmus giallolateralus Ho sp. nov.

( Fig. 4 B, 5D, 5E, 5F, 6C, 6D, 7C, 7D, 8C, 8D, 9A, 10C, 10D, 13)

Type. Holotype, TAIWAN: Dongjyu, Lienchiang County, Taiwan, 1 male (bathed samples), 26-IV-2010, Jian-Hua Wang. ( ESRI);

Paratype: TAIWAN: Dongjyu, Lienchiang County, Taiwan, 2males, 2 females, 23-V-2011, Hua-Te Fang. ( ESRI). Holotype is deposited in ARI; four paratypes are deposited in NMNS and ESRI.

Etymology. This species is named for its yellowish margin on the elytra. Giallo- means the color yellow and - lateralus means the lateral margin.

Diagnosis. The enlarged flagellar segments 4–9 are similar to R. flavus which occurs in Malaysia and Thailand, but in R. flavus a lens-like sensillum adheres to each enlarged segment ( Kawashima and Satô, 2001). In Matzu Archipelago, R. beigansis and R. giallolateralus can be simply distinguished from males in the elytra, and the genitalia. The elytra of R. giallolateralus have a yellow margin which is lacking in R. beigansis . Also, there are clear differences in the number of segments of the antennae and maxillary palps, and in the relative position and shape of the female labial palps. In R. beigansis the antennae are 5-segmented, the maxillary palps are 4 segmented, and the labial palps ( Fig. 9 A, 9B) are slender and protrude beyond the anterior margin of the head. In R. giallolateralus the antennae are 8-segmented, the maxillary palps are 5 segmented, and the labial palps are wider and shorter, almost not reaching the anterior head margin.

Male. Body mostly dark brown, dorsal surface covered with light yellow pubescence. Head and pronotum shiny. Head capsule black; compound eyes blackish, extending to upper and lower area, concave dorsally; antennae brown; mandibles dark brown; maxillae dark brown; labium dark brown to brownish; pronotum dark brown; elytra dark brown, with obvious orange-yellowish or yellowish brown on each margin; ventral surface of thorax orangeyellowish; coxae and trochanters orange-yellow, femora mainly brown to dark brown, orange-yellow at base and apex, tibiae and tarsi dark brown; abdomen dark brown to blackish, with light yellow or white markings along posterior margin of segments.

Body ovoid from above, blunt at front and thinnest behind, punctuation separated in dorsal view.

Head wider than long, semi-circular, widest at basal margin, but narrower than the apical and basal width of pronotum, punctures separated and surrounding antenna and mouthparts; compound eyes meniscus-like in dorsallateral view, concave basally.

Antennae 12-segmented, 1.77 mm in length; scape short and thick; pedicel, similar to scape in shape; 1st to 3rd flagellar segments filiform, weakly broad posteriorly with length longer than scape and pedicel; 4th to 9th flagellar segments slightly serrate, length and shape are almost the same, lens-like sensillum located at antero-ventral side of 9th flagellomere; 10th flagellomere (terminal segment) spindle shaped, slender, and tapering at its apex.

Pronotum transverse, semi-circular in dorsal view, anterior margin very broadly rounded with no distinct anterolateral corners and merging into the divergent lateral margins; right angles formed at the junction of lateral and basal margin, basal margin straight or weakly wavy, the widest part of pronotum, but a little narrower than humeral width of elytra; punctation separated, spread uniformly over surface; PW/HW 1.14, PW/PL 1.51, PW/PA 1.17, PW/EW 0.68, PW/EHW 0.83.

Elytra elongate, contiguous along inner margin, outer margins slightly expanded; extending to, or slightly before abdominal apex; lateral margin straight and nearly parallel-sided, width contracting over apical 1/7; punctation separated, pubescence uniform over surface; EL/PL 5.37, EL/EW 2.40, EW/EHW 1.24.

Legs slender; femur with lateral margin straight and parallel-sided; tibia slightly conical, thicker at apex than base; tarsi 5-segmented, each segment clavate, with 2 claws apically, empodium or arolium not distinguished; HFL/HTL 0.96.

Male genitalia 0.9 mm in length, trilobed without punctation and pubescence, basal plate large, covering the basal part of aedeagus and parameres in ventral view, basal margin arcuate and protruded towards base without angle, basal 1/2 of lateral margins dispersed, gradually separated towards apex, then subparalleled on apical 1/2; aedeagus shorter than parameres, bluntly cone-like, lateral margin arcuate, gradually converging towards bluntly rounded apex, grooves not apparent over surface; parameres dipper-like, apical parts protruding towards apex ventrally and surrounding the outer side of the aedeagus; basal margin narrow, forming an incisive arcuate-shape at the basal end, the outer lateral margin straight, converging rapidly towards inner side near apex, forming right angles at marginal junction, inner side straight in dorsal view, dark bands located at basal 1/2.

Female. Larviform, 18.52± 1.64 mm (range: 16.32–20.44, n=9) in length, 2.35± 0.17 mm (range: 2.18–2.72, n=9) wide at basal margin of pronotum. Body yellowish or brownish. Head small, with small compound eyes. Antennae 8-segmented, maxillary palp 5-segmented, labial palp 3-segmented. Labial palps are tightly shrunk. There are two sets of luminous organs. The first set is a large luminous organ on 7th ventral abdominal segment and the second consists of three spot-like luminous organs on most segments. Two on both body sides extending from the mesothorax to the 9th abdominal segment, and one dorsally from the middle of the mesothorax to the 8th abdominal segment.

Measurement in mm. BL: 10.99 (holotype) (range: 10.84–11.02); HW: 2.35 (range: 2.33–2.38); PL: 1.77 (range: 1.77–1.82); PA: 2.29 (range: 2.29–2.31); PB: 2.68 (2.68–2.99); PW: 2.68 (range: 2.68–2.74); EL: 9.51 (range: 9.51–10.17); EW: 3.97 (range: 3.91–3.97); EHW: 3.21 (range: 3.21–3.30); HFL: 2.12 (range: 2.11–2.15); HTL: 2.20 (range: 2.12–2.20).

Distribution. TAIWAN: Dongjyu, Matzu Archipelago, Lienchiang County.

Remark. The vegetation in habitats of R. giallolateralus consists of thick grass mainly, or of forests or lofty herbs, e.g. Miscanthus floridulus (Labill.) . Adults occur in February to April, females are active between 6:30 and 8:00 at night. The behavioral display, fecundity and characteristics of the eggs are similar to Rhagophthalmus beigansis .

Discussion

Rhagophthalmidae species have little capacity to migrate due to the wingless form of adult females, and it would be expected that isolated populations like the two described here would diverge significantly. Two Rhagophthalmus species addressed here were found in Beigan islet and Dongjyu islet separately. These islets are less than 40 km apart, but no population of these species was found in other neighboring islands. With virtually no capacity to migrate the species are totally dependent on the existing habitat of these islets and conservation of these fragile environments is thus very important. Habitat fragmentation and human activities have already been identified as the major stress to such island populations ( Atkinson, 1989; Hess, 1990). Since the populations of these two Rhagophthalmus species were distributed in a somewhat fragmentary nature across the islands, further study could evaluate the habitat fragmentation.

Wittmer and Ohba (1994) discovered R. ohbai in Iriomote island. Because of its distinctive distribution, ecological habitat, and biological features, the Ministry of the Environment, Japan designated R. ohbai as an emergency conservative species. The species was then investigated in a series of related studies ( Ohba, 1997). The islets of Beijan and Dongjyu, are only 6.44 and 2.64 km 2 in area. Because of the instability and vulnerability in island ecology, and the dependence of Rhagophthalmus on the existing habitat, further investigation of the two Rhagophthalmus distributed in Matzu Archipelago is necessary with the aim of protecting the fragile environment.

Few investigations thus far have focused on the behavior, habitat and breeding methods of Rhagophthalmidae ( Ohba et al., 1996; Ohba, 1997, 2004). Male genitalia have to date presented the most useful characteristics for identification of Rhagophthalmus species ( Wittmer & Ohba, 1994; Kawashima & Satô, 2001; Kawashima & Sugaya, 2003; Li et al., 2008). Males, being nocturnal and non-luminous are difficult to collect ( Li et al., 2008). Increased awareness of the genus and its distribution and improved collection methods should hopefully address this situation.

Figures

FIGURE 4. Male antennae of Rhagophthalmus spp. A. R. beigansis Ho sp. nov.; B. R. giallolateralus Ho sp. nov.

FIGURE 9. Female of Rhagophthalmus spp. A. R. giallolateralus Ho sp. nov.; B. R. beigansis Ho sp. nov.