Amplaria Chamberlin, 1941

Shear, William A., 2021, The millipede family Striariidae Bollman, 1893. II. New records and species of the genus Amplaria Chamberlin, 1941 (Diplopoda, Chordeumatida, Striarioidea), Zootaxa 4908 (2), pp. 205-224 : 207-208

Genus Amplaria Chamberlin, 1941 .

Amplaria Chamberlin, 1941, p. 9 . Type species: Amplaria eutypa Chamberlin, 1941 (by monotypy). Shear & Krejca, 2007, p. 25. Shear, Nosler & Marek, 2017, p. 234. Shear, 2020, p. 282.

Speostriaria Causey, 1960, p. 26 . Type species: Striaria shastae Causey, 1958 (by original designation). Synonymized by Shear & Krejca (2007).

Vaferaria Causey, 1958, p. 180 . Type species: Striaria imberbis Loomis, 1936 (by original designation). Synonymized by Shear (2020)

Included species: Amplaria nazinta ( Chamberlin, 1910) , Amplaria eutypa Chamberlin, 1941 , Amplaria imberbis ( Loomis, 1936) , Amplaria eldora (Chamberlin, 1953) , Amplaria shastae (Causey, 1960) , Amplaria muiri Shear & Krejca, 2007 , and Amplaria adamsi Shear & Krejca, 2007 , and the ten new species described below.

Secondary sexual characters of the males: The characters of Amplaria have been discussed in some detail by Shear and Krejca (2007) and Shear (2020). Most of the taxonomically useful characters are to be found, as usual in millipedes, in the secondary sexual modifications of the males, including the gonopods and ninth legs. Such characters are of variable occurrence from species to species and hence useful in diagnosing new taxa. Males of Amplaria may or may not have pronounced hooks or sinuate spines at the lateral corners of the labrum ( Figs. 8 , 15 ; mistakenly referred to as the mentum in Shear & Krejca [2007]). The mandibular stipes is sometimes angular distally and with a sawtooth posterior edge. The collum in males is both longer and broader than in females. The first legpair may be much larger than the second or about the same size, and some of its podomeres may bear long, needle-like setae, or highly modified twisted, spatulate ones ( Figs. 16, 17 ; sometimes both types are present). The second legpair carries the openings of the vasa deferentia on the coxae as short, extensible, membranous tubes ( Fig. 40 ), and the trochanters have variously developed distal knobs with specialized setae ( Fig. 32 ); the trochanters may be fused to the coxae and the coxae themselves fused bilaterally ( Fig. 6 ). The telopodites of the second legpair may be shorter and more slender than those of the first pair, or subequal to them. The third legpair has much enlarged coxae, extended into flask-like structures (i.e., Fig. 21 ), the tips of which have specialized curled setae and insert at rest into the openings of the vasa deferentia on the second coxae or are held in front of the male’s “face”; the flasks may be large and tightly appressed to one another in the midline ( Fig. 6 ), or small, well separated and divergent; the telopodites are usually reduced and the prefemora may be modified with a distoventral lobe ( Fig. 6 ). Behind the third coxae, prominent bars extend on either side from the third pleurotergite, supporting the third coxae ( Fig. 13 ). The coxae of the fourth and fifth legpairs may have a deep, distal depression and be covered in long, fine setae ( Fig. 41 ). The fourth, fifth and sixth legpairs are enlarged, with flattened podomeres, as are the seventh legs, which in addition have enlarged coxae that cover the bases of the gonopods.

The characteristic gonopods are described and illustrated in detail in Shear (2020) and in this paper. Fundamentally, each gonopod consists of two prominent angiocoxites (anterior and posterior), a flagellocoxite, and a twolobed colpocoxite ( Figs. 45–57 ). The ninth sternite is broad and bowl-shaped, accommodating the resting gonopods. The ninth legpair (i.e., Fig. 3 ), often incorrectly referred to as “posterior gonopods,” are strongly reduced and consist only of a coxa, which may have a short apophysis at the mediodistal margin; a small, probably vestigial coxal gland pore; and a flattened single-articled telopodite which loosely articulates with the ventral edge of the seventh pleurotergite ( Fig. 36 ). The telopodite may have a long, finger-like mesal extension ( Fig. 3 ). The tenth legpair resembles subsequent pairs but has large coxal gland pores.

Nonsexual characters: The number of ommatidia varies between species from none to about 15. The ommatidia are of irregular shape and size and usually poorly pigmented. Evidently unique to Amplaria is a specially modified type of seta found on the legs ( Fig. 23 ). Progressing distally on any leg, these setae transition gradually to ordinary ones. A character that has previously been overlooked affects the terminal segment, or pygidium. In several species, the pygidium is elongated and flattened ( Figs. 19 , 20 ) and the notches between the three characteristic lobes are much deeper than in other species. The degree to which this is the case varies from species to species. The waxy coating, or cerotegument, is obvious in many of the SEM images presented here, as it cracks and partially flakes off during handling. Specimens of Amplaria species may be white to uniformly pale tan, or with four purplish-brown spots evenly spaced across each ring, two near the pleurotergal ventral edge on each side and two dorsally, on either side of the median sulcus. Seen from above, the dorsal spots blend into what appear to be two continual dark stripes on a light background (the “two-striped” pattern). In those species darkly pigmented, the collum and pygidium are sometimes a strongly contrasting white.

Species groups: The distribution of the characters briefly listed above and the unique forms they take in some of the new species, initially suggested to me that perhaps as many as three new genera could be named and described. However, due to the few and scattered records, implying the existence of additional species and the relatively uniform gonopod plan, I decided only to designate three species groups in addition to the “classic” Amplaria species obviously close to the type (which I have left ungrouped). When more collecting has been done and we know more about the full range of species now in the genus, and genetic data perhaps becomes available, these species groups may be elevated to separate genera.

Figures

FIGS. 8–10. Amplaria fontinalis. Fig.8. Head and first 3 rings of male, ventral view. Fig. 9. Left gonopod, mesal view. Fig. 10. Gonopod tips, posterior view.

FIGS. 14–19. Amplaria rykkenae, A. arcata. Fig. 14. Amplaria rykkenae, posterior end of male, dorsal view. Figs. 15–19. A. arcata. Fig. 15. Left side of head and first two legpairs of male, anterior view. Fig. 16. Tarsus of legpair 1, lateral view. Fig. 17. Special setae of tarsus 1. Fig. 18. Second and third legpair of male, ventral view. Fig. 19. Pygidium, ventral view.

FIGS. 37–40. Amplaria umatilla, A. cervus. Figs. 37. Amplaria umatilla, right gonopod, mesal view. Figs. 38–40. A. cervus. Fig. 38. Right gonopod, mesal view. Fig. 39. Legpair 9 of male, anterior view. Fig. 40. Right second coxa and trochanter, posterior view.

FIGS. 32–36. Amplaria staceyi, A. umatilla. Figs. 32–34. Amplaria staceyi. Fig. 32. Apophysis of left leg 2 of male, ventral view. Fig. 33. Left gonopod of male, lateral view. Fig. 34. Right gonopod of male, mesal view. Figs. 35, 36. A. umatilla. Fig. 35. Second and third legpair of male, ventral view. Fig. 36. Gonopod complex, lateral view.

FIGS. 5–7. Amplaria crawfordi, A. fontinalis. Figs. 5, 6. Amplaria crawfordi. Fig. 5. Gonopods, anterior view. Fig. 6. Legpairs 2 and 3, ventral view. Fig. 7. A. fontinalis, left gonopod, lateral view.

FIGS. 20–24. Amplaria arcata. Fig. 20. Posterior end of male, lateral view. Fig. 21. Legpair 3 of male, anterior view. Fig. 22. Gonopod complex, ventral view. Fig. 23. Special setae of legpair 3.

FIGS. 11–13. Amplaria rykkenae. Fig. 11. Gonopods, anterior view. Fig. 12. Gonopod tips, anterior view. Fig. 13. Legpair 9, anterior view.

FIGS. 41–44. Amplaria menocino, A. flucticulus. Fig. 41. Amplaria mendocino, legpairs 2–4 of male, ventral view. FIGS. 42–44. A. flucticulus. Fig. 42. Head, collum and rings 2–6, dorsolateral view. Fig. 43. Legpairs 2 and 3 of male, lateral view. Fig. 44. Right gonopod, lateral view.

FIGS. 45–54. Drawings of gonopods of Amplaria species. Fig. 45. Left gonopod of A. nazinta, lateral view. Fig. 46. Tip of anterior angiocoxite of A. nazinta gonopod, lateral view. Fig. 47. Right gonopod of A. crawfordi, mesal view. Fig. 48. Tip of anterior angiocoxite of A. crawfordi, lateral view. Fig. 49. Right gonopod of A. fontinalis, mesal view. FIG. 50. Tip of anterior angiocoxite of A. fontalis, posteriolateral view. Fig. 51. Right gonopod of A. rykkenae, mesal view. Fig. 52. Right gonopod of A. rykkenae, lateral view. Fig. 53. Right gonopod of A. baughi, lateral view. Fig. 54. Right gonopod of A. umatilla, lateral view.

FIGS. 55–59. Drawings of gonopods of Amplaria species. Fig. 55. Right gonopod of A. umatilla, mesal view. Fig. 56. Right gonopod of A. cervus, mesal view. Fig. 57. Right gonopod of A. mendocino, mesal view. Fig. 58. Right gonopod of A. flucticulus, lateral view. Fig. 59. Right gonopod of A. flucticulus, mesal view.

FIGS. 1–4. Amplaria nazinta, A. crawfordi. Figs. 1–3. Amplaria nazinta. Fig. 1. Rings 8 and 9, lateral view. Fig. 2. Gonopods, anterior view. Fig. 3. Legpair 9, anterior view. Fig. 4. A. crawfordi, right leg 9, anterior view.