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

description: Cyclosomus marginatus Motschulsky
Figures 8, 14D, 16D, 17D, 21
Cyclosomus marginatus Motschulsky, 1864:200. LECTOTYPE, here designated, a female, deposited in ZMMU, labeled: “Ind. Or.” [handwritten]/ “ Cyclosomus marginatus Motsch. Ind. Or. ”/ “ C. marginatus Motch = C. suturalis Wied. H.E. Andrewes det.”/ “ LECTOTYPE Cyclosomus marginatus Motschulsky 1864 design. by D.H. Kavanaugh & M. Cueva-Dabkoski 2023” [red label]. Type locality: eastern India. Chaudoir 1876: 32.
Cyclosomus suturalis, Andrewes (1921:166, 1924 a:464); Csiki (1932:1295); Lorenz (2005:452).
Notes on types and nomenclature. See below under C. suturalis (Wiedemann) for further discussion about types. We must note here that if, as discussed above, C. marginatus and C. inustus were to be considered conspecific, then the name C. marginatus has priority. We choose not to propose that synonymy at this time.
Diagnosis. Adults of C. marginatus can be distinguished from those of other Cyclosomus species in Asia by the following combination of character states: Body size medium for genus, BL male = 7.3 mm, female = 7.0 mm; body form (Fig. 8A) roundly ovoid (ratio BL/EW = 1.46 to 1.49; ratio EL/EW = 0.94 to 0.96), with elytra widest at or near mid-length; dorsal surface (Figs. 8A) with distinctly contrasting pale and dark areas; pronotum (Fig. 14D) relatively broad (ratio PWM/PL = 2.67 to 2.92) and more broadened basally (ratio PWM/PWA = 1.65 to 1.67), with disc rufopiceous to black, lateral pale bands broad and well-defined, anterior angles broader, lateral margins not sinuate or very faintly sinuate near anterior angles; free apex of prosternal intercoxal process medium in length (as in Fig. 15B); elytra (Fig. 8A) pale yellowish-brown with basal, middle and longitudinal dark bands present and dark reddish brown to black, preapical dark spot absent, basal and middle bands of average thickness, 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 a narrow, oblique dark line; elytral striae moderately impressed, elytral intervals flat or nearly so; elytral epipleura with long setae only in humeral and subhumeral areas, setae in apical two-thirds distinctly shorter; median lobe of male genitalia with shaft of approximately equal thickness throughout, ventral curvature straightened subapically in lateral aspect (Fig. 16D), apical lamella short and smoothly rounded in dorsal aspect (Fig. 17D); specimen not from Philippine Islands.
Specimens of C. marginatus are most similar to those of C. inustus, C. pallidus, and C. vespertilio. Features distinguishing specimens of C. marginatus from those of C. inustus are discussed above in the Diagnosis section for the latter species. The elytra of all known specimens of C. marginatus have the middle dark band present and in the form of a compound-W, whereas C. pallidus members have the middle band absent. Members of C. marginatus differ from those of C. vespertilio in having the free apex of the prosternal intercoxal process moderate in length, as in Fig. 15B, rather than short, as in Fig. 15D. Most members of these two species also differ in the development of the middle dark band. In the all three known specimens of C. marginatus, the band is relatively thin and in the compound-W form (Fig. 8A). In contrast, the middle dark band in C. vespertilio is similarly shaped but distinctly thicker (Figs. 13A, 13B) in most specimens, as thin as in C. marginatus in only two specimens that we have seen (Fig. 13D).
Habitat distribution. Unknown, but presumed to be restricted to the sandy shores of medium to large rivers at low elevation, like members of most other species of the genus.
Geographical distribution. We have examined a total of three specimens (one male and two females) from the following localities: BANGLADESH / INDIA / MYANMAR: “Bengal” (May 1809 [one male; ZMUC]). Eastern India (“ India Or. ”) [one female; ZMMU]. Northern India (“ N India ” ([one female; NHMUK]).
The lectotype specimen from ‘eastern India’ could have been collected anywhere in present-day India, Bangladesh, or Myanmar, the specimen from “Bengal” from anywhere in West Bengal (India) or Bangladesh, and the specimen from ‘northern India’ from anywhere from Pakistan to Myanmar along the southern base of the Himalaya. Consequently, the range of this species remains undefined (Fig. 21) and problematic. The record of its occurrence in “Indo-China” (Andrewes 1921) probably is based on a misidentification of specimens of C. inustus, which species Andrewes subsequently described (Andrewes 1924) as distinct (see above). Some other records from India may have been based on misidentified specimens of C. vespertilio, which is described below. If C. inustus is actually restricted to sandy sea coast areas everywhere it occurs as it is in Taiwan and apparently in southeast coastal China, then records from inland parts of Indochina (i.e., in Cambodia, Laos, and Thailand) may, in fact, represent either C. marginatus or another, undescribed species.
Geographical variation. There is insufficient material available at present to recognize any possible geographical variation in this species, unless the specimens from inland part of Indochina are considered as conspecific with C. marginatus rather than C. inustus (see comments about geographical variation in that species above).
Geographical relationships with other Cyclosomus species. In the absence of any specific locality records for this species, its syntopy or even sympatry with any other congeners cannot be confirmed. Cyclosomus suturalis is also known from “Bengala”, again without specific locality, so it is possible that these species co-occur. Also, eastern India is within the broad geographical range of C. flexuosus (recorded from northernmost West Bengal) and at the western limit of the range of C. inustus, so there is at least potential for co-occurrence with either or both of these species.
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 511-513, DOI: 10.5281/zenodo.11512952