Crematogaster cedrosensis

CREMATOGASTER CEDROSENSIS WHEELER, 1934 A STAT. REV., STAT. NOV.

Crematogaster lineolata cedrosensis Wheeler, 1934a: 136 .

Eight syntype workers, Cedros Island, Baja California, Mexico, 5 June 1925 (Keifer) (CASC, LACM, MCZC) (four workers in CASC, two workers in LACM and one worker in MCZC examined); one worker in CASC here designated lectotype ( CASENT0863153 ).

Crematogaster opaca cedrosensis Wheeler View in CoL ; Enzmann, 1946: 94.

Crematogaster opaca cedrosensis View in CoL a junior synonym of C. laeviuscula: Morgan & Mackay, 2017: 197 View in CoL ; here overturned.

Worker measurements (N = 6): HW 0.82–0.96, HL 0.83– 0.94, SL 0.66–0.77, WL 0.93–1.05, MtFL 0.71–0.83, MSC 0, A4SC 0–2, PP-SL /HW 0.09–0.12, CI 1.00–1.05, OI 0.25–0.27, SI 0.73–0.81, MtFL /HW 0.83–0.88, SPL/ HW 0.18–0.21, SPTD/HW 0.43–0.50.

Discussion: Described from Cedros Island off the west coast of Baja California, C. cedrosensis was originally treated as a subspecies of C. lineolata , then combined with C. opaca by Enzmann (1946: 94) and finally synonymized under C. laeviuscula by Morgan & Mackay (2017: 197). In fact, C. cedrosensis shows little similarity to those three species. It can be characterized as follows: relatively small species (HW 0.82–0.96), with little standing pilosity (MSC 0, A4SC 0–2); frons and mesosoma dorsum strongly shining, with weak reticulate-striate sculpture on parts of the latter; promesonotum joining the dorsal face of the propodeum without a distinct step (lateral view); and propodeal spines relatively short and directed posterad (SPL/ HW 0.18–0.21, SPTD/HW 0.43–0.50). Crematogaster cedrosensis is most similar in appearance to certain West Coast populations of C. hespera with darkcoloured workers (see below). Metric measurements and indices do not allow unequivocal separation of the two, but C. cedrosensis workers tend to have a less broad head (CI 1.00–1.05 vs. 1.04–1.11 in C. hespera ). A more reliable distinguishing trait is the scarcity of standing pilosity in C. cedrosensis : there are no setae on the mesosoma dorsum and almost none on the fourth abdominal (first gastric) tergite (MSC 0, A4SC 0–2 vs. MSC 3–14, A4SC 9–26 in C. hespera ). In addition, the postpetiolar seta is disporportionately shorter in C. cedrosensis ( PP-SL /HW 0.09–0.12, versus 0.13–0.21 in C. hespera ).

Distribution and biology: This species is known only from the type locality (Cedros Island) and a few adjacent locations on the mainland of Baja California. T h e n e a r e s t k n o w n s a m p l e s o f C. c e d r o s e n s i s and C. hespera were collected less than 50 km apart, and they show no evidence of converging in appearance. No genetic sequence data are available for C. cedrosensis , nor is anything known about its biology.