Bidentogon californicus (Chamberlin,1918)

Shear, William A. & Marek, Paul E., 2021, Three new genera and eighteen new species of miniature polydesmid millipedes from the northwestern United States (Diplopoda, Polydesmida, Polydesmidae), Zootaxa 4975 (1), pp. 81-126 : 88

Bidentogon californicus (Chamberlin,1918)

Figs 1–6

Brachydesmus californicus Chamberlin 1918:9 .

Bidentogon helferorum Buckett & Gardner 1968:198 ; Shear, 1972:490.

Bidentogon californicus, Shelley, 2003:10 .

Diagnosis. The terminal zone of the gonopod (tz, Fig. 6 ) is acute, not expanded as it is in the other known species of the genus. The anterior marginal row of setae on the collum ranges in number from 14 to 16 ( Fig. 1 ).

Notes. After some confusion, the name of this species was finally settled by Shelley (2003). Shear (1972) had discovered the supposed type material of Chamberlin’s Brachydesmus californicus in the collections of the Museum of Comparative Zoology and redescribed that species while applying the genus name Bidentogon (at the time Chamberlin described the species, any polydesmid with 19 rings was placed in Brachydesmus , now understood as an exclusively European genus). However, Shelley (2003) was able to show that B. helferorum was actually a synonym of B. californicus , and provided the new name B. expansus Shelley, 2003 , for Shear’s concept of B. californicus .

Buckett & Gardner (1968) provided a good detailed description of this species (as B. helferorum ), supplemented by Shear (1972) with additional illustrations. Shelley (2003) documented and mapped many new localities from Alameda, Marin, Mendocino, San Mateo, Santa Clara and Santa Cruz counties in California. Here we provide SEM illustrations for the first time ( Figs 1–6 ). Using material temporarily mounted on microscope slides, it was possible to trace the seminal canal out to the tip of the shorter gonopod branch, which is therefore referred to as a solenomere. No vesicle could be seen and the course of the canal is more or less direct, though it does sharply change direction laterad near the base of the solenomere. The simple, acute, terminal zone distinguishes this species from B. expansus , in which the terminal zone widens distally.

Distribution. San Francisco Bay region of California, and north to Mendocino County ( Shelley, 2003)

New records. CALIFORNIA: Marin Co.: 1 mi. west of Bolinas (37.308°, -122.706°), 16 January 1960, C. Judson, m ff ( FSCA); 3 mi northwest of Inverness (38.124°, -122.903°), 8 May 1976, A. Newton, M. Thayer, m, f ( FMNH); 6 mi east of Point Reyes Station (38.094°, -122.735°), A. Grigarik et al., 1 March 1960 ( FSCA) . San Mateo Co.: 0.5 mi southeast of Half Moon Bay (37.462°, -121.530°), 18 May 1954, R. Schuster mm ff ( FSCA) .

Figures

FIGURES 1–6. Bidentogon californicus Buckett & Gardner. 1. Head and anterior rings, dorsal view. 2. Midbody ring, dorsal view. 3. Epiproct, lateral view. 4. Anterior end of male, ventral view. 5. Gonopods in situ, ventral view. 6. Gonopod tips, ventral view. Abbreviations: sm, solenomere; tz, terminal zone. SEM stub WS33-8.