Cyclosomus Latreille 1829
Creators: name: Kavanaugh, David H.
name: Cueva-Dabkoski, Mollie
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Carabidae
Cyclosomus

description: Genus Cyclosomus Latreille, 1829
Scolytus Fabricius, 1790:221, in part [junior homonym of Scolytus Geoffroy, 1762] (type species Carabus limbatus Fabricius, 1801, designated by Latreille (1810:426). Fabricius (1792:180); Bousquet (2012:89).
Cyclosomus Latreille, 1829:394 (type species Carabus flexuosus Fabricius, 1775, by monotypy).
Diagnosis. Adults of Cyclosomus species can be distinguished from those of other Asian carabid species by the following combination of character states: Body medium-sized, BL = 6.5 mm to 9.5 mm; body form broadly ovoid (e.g., Fig. 3), Omophron -like; head with two pairs of supraoribital setae; labrum with anterior margin deeply emarginate; mentum with medial tooth present, apically emarginate; pronotum (Fig. 14) very broad, trapezoidal, almost as wide as elytra at humeral angles, distinctly widest at or near base; elytra broadly rounded apically, elytral basic color pattern as in Fig. 3B; middle and hind tibiae with medial spurs long and serrulate (Fig. 2A); front tarsomeres 1 to 3 markedly expanded laterally (Figs. 2B, C) in both males and females; middle tarsomeres 1 to 3 broad and with pads of adhesive squamosetae (Stork 1980) ventrally in males (Figs. 2D, E), narrower and without ventral setal pads in females.
Diversity: At present, six species are recognized in the Afrotropical Region and seven species in the Asian fauna. We here recognize nine Cyclosomus species as occurring in Asia, with two of these new to science.
Key for Identification of Adults of Cyclosomus species of Asia
Both male and female adults of Cyclosomus species from the region can be identified using the key below. We have avoided gender-specific features as much as possible in creating the key, and where features unique to males are used, they are presented only as secondary in importance. However, these features can be very helpful in confirming the identification of males. Male specimens of all species included in the key have small pads of adhesive setae on the ventral surfaces of front tarsomeres 1 to 3. Females have no such pads. Although in most carabid beetle species these front tarsomeres are also distinctly broader in males than in females, in the Asian Cyclosomus species these differences are very slight and therefore difficult to assess. Contributing to this difficulty is the fact that both males and females have the basal three tarsomeres asymmetrically expanded laterally as flat plates that undoubtedly aid in digging into the sandy substrate they inhabit. More reliable features for distinguishing the sexes are middle tarsomeres 1 to 3, which are distinctly broader in males than in female and have ventral adhesive setae, which are absent from females. We recommend that users of the key review the cautions given in the section entitled “Color and color patterns” under Materials and Methods above because the elytral color pattern is highly varied within some species and similar among at least some members of different species.
1 Pronotum (Fig. 14A) with anterior angles narrow, distinctly acute, lateral margins slightly to distinctly sinuate near anterior angles, disk dark piceous to black, with lateral pale bands well-defined and very narrow; median lobe of male genitalia with shaft evenly arcuate and tapered to a thick apical lamella, slightly ventrally deflected in lateral aspect (Fig. 16A), shaft slightly broadened for most of its length, then tapered to base of short, narrow, smoothly rounded apical lamella in dorsal aspect (Fig. 17A)....................................................................... Cyclosomus acutangulus Kavanaugh & Cueva-Dabkoski
1’ Pronotum (Figs. 14 B-I) with anterior angles broader, lateral margins not sinuate or (in very few specimens) faintly sinuate near anterior angles, lateral pale bands wider, well-defined or not, male genitalia as in Figs. 16 B-H, 17B-H.................................... 2
2 (1’)Elytra without (Figs. 7A, 7C, 8 -10,13) a preapical spot or with only a small and faint (Fig. 7D) spot (seen in some specimens from inland parts of Indochina)................... 3
2’ Elytra (Figs. 5, 6, 11, 12,) with distinct preapical dark spot......................... 7
3 (2)Elytral epipleuron with long setae over entire length, visible from dorsal aspect in most specimens (Fig. 10A) [but best viewed from below because setae may be bent posteriorly in some specimens]; pronotum (Fig. 14F) relatively narrow (ratio PWM/PL = 2.06 to 2.33) and less broadened basally (ratio PWM/PWA = 1.45 to 1.59), with disc piceous to black and lateral pale band wide and well-defined; free apex of prosternal intercoxal process long (as in Fig. 15C); elytral dark pattern varied (Figs. 10A, C), with basal and middle bands of average to greater than average thickness; median lobe of male genitalia with shaft arcuate basally and nearly straight subapically, tapered to a long and pointed apical lamella in lateral aspect (Fig. 16E), shaft moderately broad basally, gradually tapered to moderately broad and apically blunted, sublaceolate apical lamella in dorsal aspect (Fig. 17); specimen from Philippine Islands (Fig. 21).............................................. Cyclosomus philippinus Heller
3’ Elytral epipleuron with long setae only in humeral and subhumeral areas, setae in apical two-thirds distinctly shorter; pronotum (Figs. 14 C, D, E, I) relatively broader in most specimens (ratio PWM/PL = 2.33 to 2.93) and more broadened basally (ratio PWM/PWA = 1.63 to 1.75), with disc varied in color (pale tan-orange to black) and lateral pale band well-defined or not; free apex of prosternal intercoxal process varied in length, from long to short (Fig. 15); elytral dark pattern varied, with basal and middle bands of average to less than average thickness or middle band absent; median lobe of male genitalia not sublanceolate, rounded in dorsal aspect (Figs. 17C, D, H); specimen not from Philippine Islands ........................... 4
4 (3’)Pronotum (Fig. 14C) relatively longer and narrower (ratio PWM/PL less than 2.50), with disc varied in color (rufous to piceous) and lateral pale bands medium-width and well-defined; free apex of prosternal intercoxal process long (as in Fig. 15C); body form (Figs. 7A, C, D) more elongate-ovoid (ratio BL/EW = 1.47 to 1.53), with elytra widest at or slightly anterior to mid-length; elytral dark pattern varied in both form and color (Figs. 7A, C, D), with dark maculae rufous to piceous and with basal and middle bands of average to less than average thickness and continuity or middle band absent; elytral striae very deeply impressed, elytral intervals (especially intervals 3 to 5) slightly but distinctly convex; median lobe of male genitalia long and more slender, shaft of approximately equal thickness throughout, ventral curvature gradually and only slightly arcuate in apical two-thirds in lateral aspect (Fig. 16C), apical lamella longer, rounded apically, and not or only slightly narrowed basally in dorsal aspect (Fig. 17C); specimen from southern Asia, from northeastern coastal India, through Indochina, to coastal southeastern and eastern China and Taiwan (Fig. 20)....... Cyclosomus inustus Andrewes
4’ Pronotum (Figs. 14D, E, I) shorter and very broad (ratio PWM/PL equal to or greater than 2.65); body form (Figs. 8A, 9A, 13A, 13C, 13D) shorter in most specimens (ratio BL/EW = 1.36 to 1.49), more roundly ovoid, broader apically; elytral dark pattern varied in both form and color; elytral striae less deeply impressed in most specimens, elytral intervals flat or nearly so; median lobe of male genitalia varied in form (Figs. 16D, H)................... 5
5 (4’)Dorsal surface (Fig. 9A) mainly pale tan-orange, with only pronotal disc, elytral basal dark band and longitudinal dark band on elytral interval 1 slightly darker brown, middle dark band absent; pronotum (Fig. 14E) very broadly flattened laterally (especially anteriorly), lateral pale bands very broad and only slightly contrasting with color on disc; free apex of prosternal intercoxal process short (as in Fig. 15D); specimen from southeastern Pakistan (Fig. 21); males unknown............... Cyclosomus pallidus Kavanaugh & Cueva-Dabkoski sp. nov.
5’ Dorsal surface (Figs. 8A, 13A, C, D) with distinctly contrasting pale and dark areas; pronotal disc darker, rufopiceous to black, with lateral pale bands broad but narrower than above (Figs. 14D, 14I); elytra pale yellowish-brown with basal, middle and longitudinal dark bands present and dark reddish brown to black; free apex of prosternal intercoxal process short (as in Fig. 15D) or medium in length (as in Fig. 15B)...................................... 6
6 (5’)Body form (Fig. 8A) roundly ovoid (ratio BL/EW = 1.46 to 1.49; ratio EL/EW = 0.94 to 0.96); free apex of prosternal intercoxal process medium in length (as in Fig. 15B); elytra with middle transverse dark band narrow, extended laterally onto interval 6, portion on intervals 2 to 4 connected to portion on intervals 5 and 6 by in narrow, oblique dark line; median lobe of male genitalia with shaft of approximately equal thickness throughout, ventral curvature straightened subapically in lateral aspect (Fig. 16D), apical lamella slightly shorter in dorsal aspect (Fig. 17D)............................. Cyclosomus marginatus Motschulsky
6’ Body form (Fig. 13A, C, D) even more roundly ovoid (ratio BL/EW = 1.36 to 1.41; ratio EL/EW = 0.88 to 0.93); free apex of prosternal intercoxal process short (Fig. 15D); elytra with middle transverse dark band varied, moderately thick in most specimens (Fig. 13A), markedly thickened (Fig. 13C) or narrowed (Fig. 13D) (much as in C. marginatus), in a few specimens; median lobe of male genitalia with shaft distinctly thicker and more arcuate, ventral curvature distinctly curved throughout in lateral aspect (Fig. 16H), apical lamella longer in dorsal aspect (Fig. 17H).... Cyclosomus vespertilio Cueva-Dabkoski & Kavanaugh sp. nov.
7 (2’)Elytral epipleuron with long setae over entire length, visible from dorsal aspect in most specimens [but best viewed from below because setae may be bent posteriorly in some specimens]; pronotum (Fig. 14B) light reddish brown to rufopiceous, with lateral pale bands moderately broad but not sharply defined, apical angles broad and broadly rounded apically; elytral dark pattern more thickly developed than average in most specimens (Figs. 5C, 6A) but less than average (Figs. 5A, 6B) in a few specimens; male median lobe with apical lamella slightly recurved dorsally in relation to ventral curvature of shaft in lateral aspect (Fig. 16B), apical lamella broadly triangular with a distinct, more narrowly-rounded projection apicomedially in dorsal aspect (Fig. 17B)........................... Cyclosomus flexuosus (Fabricius)
7’ Elytral epipleuron with long setae only in humeral and subhumeral areas, setae in apical two-thirds distinctly shorter; pronotum rufopiceous to black, with lateral pale bands narrower at least in apical half and better defined, apical angles narrower and less broadly rounded; elytral dark pattern less varied, with middle band of average (Fig. 12A) to distinctly greater than average (Figs. 11A, B, C) thickness; male median lobe with apical lamella extended in line with ventral curvature of shaft in lateral aspect (Figs. 16F, G), apical lamella in dorsal view (Figs. 17F, G) not as above........................................................ 8
8 (7’)Size slightly smaller, BL males = 7.7 to 8.1 mm, females =7.1 to 7.4; elytra (Figs. 11A, B) with middle transverse dark band extended from midline at least across interval 8, also onto interval 9 in some specimens; pronotum (Fig. 14G) relatively narrow (ratio PWM/PL = 2.25 to 2.43), piceous to black with lateral pale bands slightly narrower, distinctly defined, and slightly narrowed basally; median lobe of male genitalia with apical lamella rounded and of medium length in dorsal aspect (Fig. 17F); specimen from West Malaysia or northern Indonesia (Fig. 22).................................... Cyclosomus sumatrensis Bouchard
8’ Size slightly larger, BL males = 8.2 to 8.6 mm, female = 9.2 mm; elytra (Figs. 12A, C) with middle transverse dark band extended from midline to interval 6 in most specimens, onto interval 7 and part of interval 8 in some specimens; pronotum (Fig. 14H) relatively broader (ratio PWM/PL = 2.44 to 2.50), rufopiceous piceous to black with lateral pale bands slightly broader, less well-defined, and distinctly broadened basally; median lobe of male genitalia with apical lamella short and bluntly triangular in dorsal aspect (Fig. 17G); specimen from eastern India to westernmost Yunnan (Fig. 22).............. Cyclosomus suturalis (Wiedemann)
description: Published as part of Kavanaugh, David H. & Cueva-Dabkoski, Mollie, 2023, A Review of Genus Cyclosomus Latreille (Coleoptera: Carabidae: Lebiinae: Cyclosomini) in Asia., pp. 493-537 in Proceedings of the California Academy of Sciences 67 (21) on pages 498-501, DOI: 10.5281/zenodo.11512952