Cyclosomus inustus Andrewes

Wang, Liang-Jong, Cherng, Jyh-Jong & Kavanaugh, David H., 2017, First Records for Cyclosomus inustus Andrewes (Coleoptera: Carabidae: Cyclosomini) for Taiwan, with Notes on Habitat and Behavior, Proceedings of the California Academy of Sciences 64 (5), pp. 107-116 : 108-114

Cyclosomus inustus Andrewes in Taiwan

Cyclosomus inustus Andrewes, 1924:464-465 . Type locality: Hong Kong.

Adults of this species are moderate in size (body length 7.0 to 8. 7 mm), with a broadly ovoid and flattened body form. The base of the pronotum is only slightly narrower than the base of the elytra, giving these beetles a very stocky appearance, similar to that of many water beetles and especially to members of the carabid genus Omophron Latreille. However , they are so distinctive among beetles of the Taiwanese fauna that they cannot be confused with any other species record- ed from the island. Two particularly distinctive features include: (1) markedly modified front legs, with the lateral portion of the apex of the tibia expanded laterally, and the first and second (and to a lesser extent the third) tarsomeres with distinct finger-like lateral projections; and (2) hind legs with the medial spur of the tibia markedly elongate, nearly equal in length to the first tarsomere. No other Taiwanese carabid shares this combination of features, both of which are consider modifications for life in or on dry sand.

VARIATION IN COLOR PATTERN.— In Taiwan, variation in color pattern seen among adults of this species is illustrated in Fig. 1 . Color of the pronotal disc ranges from reddish brown ( Figs. 1A–C ) to dark brown or piceous ( Fig. 1D ). The color of the basal one-eighth of the elytra from the midline to elytral stria 5, together with the full length of elytral interval 1, ranges from reddish brown to black among individuals, and teneral specimens may have these areas entirely pale. The elytral “middle dark band” may be represented by a relatively thick, dark, jagged, roughly V-shaped band extended laterally onto interval 7 on each side ( Fig. 1D ), by a thinner, paler yet narrowly continuous band ( Fig. 1C ), or by reduced and disconnected vestiges of that band ( Figs. 1A and 1B ). The full range of this variation is seen within populations, so it appears to be simply individual variation and without an evident geographical component.

MATERIAL EXAMINED (A TOTAL OF 160 SPECIMENS).— TAIWAN: New Taipei City, Shihmen, Lingshanbi , 30.VIII.2008 , J. J. Cherng collector, 8 specimens ( TFRI); same locality, 7. IX. 2008, L.J. Wang & J.J. Cherng collectors , 16 specimens ( TFRI); same locality, 4.X.2008 , J.J. Cherng collector, 2 specimens ( TFRI); same locality, 23.V. 2009 , J.J. Cherng collector, 5 specimens ( TFRI); same locality, 10.VII. 2010 , J.J. Cherng collector, 3 specimens ( TFRI); same locality, 7.VIII.2011 , J.J. Cherng collector, 2 specimens ( TFRI); same locality, 23.V. 2009 , J.J. Cherng collector, 2 specimens ( TFRI); same locality, 17.IX. 2011 , J.J. Cherng collector, 3 specimens ( TFRI); same locality, 5.V. 2012 , J.J. Cherng collector, 2 specimens ( TFRI); same locality, 13.V. 2012 , J.J. Cherng collector, 2 specimens ( TFRI); same locality, 11.VII.2012 , J.J. Cherng collector, 9 specimens ( TFRI); same locality, 24.II.2013 , J.J. Cherng collector, 1 specimen ( TFRI); same locality, 27.VII.2013 , J.J. Cherng collector, 3 specimens ( TFRI); same locality, 3.X.2013 , L.J. Wang collector, 18 specimens ( CAS, CWT, TFRI); same locality, 19.X.2013 , J.J. Cherng collector, 2 specimens ( TFRI); same locality, 9.XI.2013 , J.J. Cherng collector, 1 specimen ( TFRI); same locality, 12.IV.2014 , J.J. Cherng collector, 1 specimen ( TFRI); same locality, 24.V.2014 , J.J. Cherng collector, 2 specimens ( TFRI); same locality, 24.VII.2016 , J.J. Cherng collector, 1 specimen ( TFRI); same locality, 25.XII.2016 , J.J. Cherng collector, 5 specimens ( TFRI); same locality, 7.I.2017 , J.J. Cherng collector, 12 specimens ( NMNS, NMW, TFRI, ZSM); same locality, 3.II.2017 , J.J. Cherng collector, 6 specimens ( TFRI); same locality, 4.II.2017 , J.J. Cherng collector, 2 specimens ( TFRI); same locality, 4.III.2017 , J.J. Cherng collector, 9 specimens ( TFRI). Kinshan, Chungjiao, 4.II.2017 , J.J. Cherng collector, 10 specimens ( CAS, CWT, TFRI); same locality, 12.III.2017 , J.J. Cherng collector, 8 specimens ( TFRI); Danshui, Shalun, 4.II.2017 , J.J. Cherng collector, 16 specimens ( TFRI); same locality, 12.III.2017 , J. J. Cherng collector, 9 specimens ( CAS, CWT, TFRI) .

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Kinshan

, C

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Danshui

, B

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Shihmen

, A.

mainland adjacent the and Taiwan in Andrewes inustus Cyclosomus of distribution Geographical.

2 IGURE F

DISTRIBUTION (Fig. 2).— This species is now recorded from coastal mainland China ( Hong Kong and Nanoa Island in Guongdong Province) and the three localities in northern Taiwan presented above.

ECOLOGICAL OBSERVATIONS.— Cyclosomus inustus inhabits the sandy sea coast of northern Taiwan (Fig. 3). It has not been found on sandy beaches without at least scattered plant cover present. Coast plants in the habitat of C. inustus include Casuarina equisetifolia L., Hibiscus tiliaceus L., Pandanus odoratissimus L., Scaevola sericea Forst. f. ex Vahl , Crinum asiaticum L., Vitex rotundifolia L. f., Artemisia capillaris Thunb. , Spinifex littoreus (Burm. f.) Merr. , Carex pumila Thunb. , Ipomoea pes-caprae (L.) R. Brown subsp. brasiliensis (L.) Oostst, Vigna marina (Burm.) Merr. , Tetragonia tetragonoides (Pall.) Kuntze , Oenothera laciniata J. Hill , Ixeris debilis (Thunb.) A. Gray , and Ixeris repens (L.) A. Gray. This habitat is apparently quite different from that of all the other Cyclosomus species for which habitat information is available. All others apparently favor the exposed sandy banks of mid- to large-size rivers or sandy lake shores ( Kavanaugh, 2015).

Adults of C. inustus have been observed in every month of the year. Like other congeneric species, they are active on the surface at night and hidden in the sand during the day. They are markedly and negatively phototaxis insects. At night, during their activity period, they are quick to burrow into the sand (Fig. 5A) if illuminated directly by the light of a flashlight. The earliest time at which adults have been observed active on the sand surface is 5:52 pm, just after sunset, in January, 2017. We observed that adults appear on the surface of the sand when the temperature on the beach is above 15°C (observations from three collecting sites during January through March). Although Nietner (1857) found adults of Cyclosomus flexuosus (Fabricius) hiding in the “driest, hottest and sandiest places that can be found” on the western coast of Sri Lanka, we have not yet determined the upper thermal tolerance of C. inustus in Taiwan or elsewhere.

In Taiwan, C. inustus adults have been observed in the field feeding on beetles, flies, and shield bugs (Figs. 5B–D). When maintained in the laboratory, they will not feed on live termites or caterpillars but will eat these same insects soon after they are dead. Consequently, we suggest that they are primarily scavengers, rather than predators.

Other carabid species found occupying the same habitat as C. inustus in northern Taiwan (i.e., are syntopic with this species) include Bembidion fusiforme Netolitzky ( Fig. 6A ), Abroscelis anchoralis anchoralis (Chevrolat) ( Fig. 6C ), Calomera angulata (Fabricius) ( Fig. 6E , Cicindela batesi Fleutiaux ( Fig. 6G ) and Cylindera kaleea angulimaculata (Mandl) ( Fig. 6H ). Adults of all of these species are diurnally active and only those of Bembidion fusiforme are also active at night (at least in some parts of Taiwan). For completeness, we provide below a checklist of all the carabid species observed during our study in sandy sea beach habitats in northern Taiwan.

A checklist of carabid species found during 2005-2017 in sandy sea beach habitats of northern Taiwan

1. Cyclosomus inustus Andrewes ( Fig. 1 A-D)

2. Bembidion fusiforme Netolitzky ( Fig. 6A )

3. Mastax brittoni Quentin ( Fig. 6B )

4. Abroscelis anchoralis anchoralis (Chevrolat) ( Fig. 6C )

5. Abroscelis anchoralis punctatissima (Schaum) ( Fig. 6D )

6. Calomera angulata (Fabricius) ( Fig. 6E )

7. Cicindela batesi Fleutiaux ( Fig. 6G )

8. Cylindera kaleea angulimaculata (Mandl) ( Fig. 6H )

9. Lophyra cancellata subtilesculpta (W. Horn) ( Fig. 6F )

10. Myriochile speculifera (Chevrolat)

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Danshui, D.

Kinshan, C.

Shihmen, A-B.

Taiwan in Andrewes inustus Cyclosomus of Habitats.

3 IGURE F

Tenebri- (beetle small a On. B. feeding Adult B-D. phototaxis negative demonstrating, sand). into Cydnidae burrowing(bug Adult shield Taiwan., A a nymphal in On. Andrewes small. D fly inustus a On. Cyclosomus ). sp. C. 5 IGURE Nesocaedius : Fonidae

Figures

FIGURE 1. Range of variation in color pattern among adults of Cyclosomus inustus Andrewes in Taiwan.

FIGURE 6. Other carabid species active on coastal sand in northern Taiwan. A. Bembidion fusiforme Netolitzky. B. Mastax brittoni Quentin. C. Abroscelis anchoralis anchoralis (Chevrolat). D. Abroscelis anchoralis punctatissima (Schaum). E. Calomera angulata (Fabricius), F. Lophyra cancellata subtilesculpta (W. Horn). G. Cicindela batesi Fleutiaux. H. Cylindera kaleea angulimaculata (Mandl).