Amastigogonus fossuliger Verhoeff, 1944

Mesibov, Robert, 2017, Iulomorphid millipedes (Diplopoda, Spirostreptida, Iulomorphidae) of Tasmania, Australia, ZooKeys 652, pp. 1-36 : 9-10

Amastigogonus fossuliger Verhoeff, 1944 Figs 1, 2A, B, 3C, 4B, 5B, 6C

Amastigogonus fossuliger Verhoeff 1944: 43, figs 6-8. Jeekel 1981: 43. Korsós and Read 2012: 45.

Syntypes.

At least 1 male and 1 female, Lake Leake, Tasmania, date and collector unknown (see Remarks, below), specimens not located.

Other material.

130 males and 12 females from 66 unique localities; details in Suppl. material 1.

Diagnosis.

Coxite process of anterior gonopod with posterodistal margin not extended; pseudoflagellum with dense field of short setae on telopodite behind pseudoflagellum tip; pseudoflagellum with distinct shoulder, the prostatic groove making an S-bend before entering the abruptly tapered tip of the pseudoflagellum.

Description.

Live males and females with more or less greenish-grey rings (Fig. 1A, C). Mature males observed with (39+4) rings, 2.1 mm midbody diameter to (63+1) rings, 3.6 mm. Cardo not deeper posteriorly (Fig. 4B). Leg 7 (only) with elongated coxa (Fig. 2A, C). Prefemoral pad ca 3/4 or more femur length (Fig. 5B). Striae on posterior metazonites reaching ca 2/3-3/4 of ozopore height.

Coxite process on anterior gonopod (Fig. 6C) with posterodistal margin not extended and folded over laterally. Telopodite with single row of prominent setae on posterior side of medial thickening to near telopodite apex, the thickening then widening and bearing dense brush of numerous minute setae. Pseudoflagellum ca 1/2 width of telopodite at base, tapering abruptly at ca 1/2 pseudoflagellum height to narrow, sharply pointed tip with rounded shoulder on anterior side of tapered section (Fig. 3C; ps), sometimes with small, tooth-like, anterodistal extension on shoulder; prostatic groove (Fig. 3C; pg) making S-bend from anterior side of pseudoflagellum into tapered tip.

Distribution.

Widespread in the eastern half of Tasmania (Fig. 7B) in dry and wet eucalypt forest from near sea level to at least 1050 m, extending across the Central Plateau to the Cradle Mountain area. Parapatric with Amastigogonus hellyeri sp. n. along the Mersey Break, a well-documented faunal divide for millipedes in north central Tasmania ( Mesibov 1999). Co-occurs with Amastigogonus tasmanianus in northeast Tasmania. Overlaps with Amastigogonus verreauxii on the Central Plateau and possibly in southern Tasmania, and to a small extent with Amastigogonus danpicola sp. n. southeast of the Fingal Valley. The far southern record on the distribution map (Fig. 7B) is for two Amastigogonus fossuliger males found on the verandah of a house at Francistown, and may represent an accidental translocation rather than a natural occurrence.

Remarks.

At least one male and one female of this species from the Lake Leake area were probably sent to Verhoeff by George Edward Nicholls, a Western Australian biologist who collected in Tasmania in 1928, 1929 and 1939 ( Nicholls 1943). Verhoeff (1936: 14) had previously thanked Nicholls for providing specimens of an unrelated millipede species from Lake Leake.

I have trouble understanding the differences in the two anterior gonopods illustrated by Verhoeff (1944), both presumably from Lake Leake specimens and possibly from the same male. Verhoeff’s fig. 6 shows a right gonopod tip in posterior view, fig. 7 a left gonopod tip in medial view. The thread-like pseudoflagellum in fig. 6 has a tooth-like extension on the shoulder and an intact posterobasal margin, while the shorter, tapered pseudoflagellum in fig. 7 has no tooth-like extension and a notched posterobasal margin. The remarkable thinness and fragility of the Amastigogonus fossuliger pseudoflagellum may be the explanation for Verhoeff’s difficulties in seeing and drawing these features. My Fig. 6C is based on a male from near the type locality, while the image in Fig. 3C is of a male from Ansons Bay, ca 100 km to the north. The only significant difference is the absence of a tooth-like extension in the latter.

Amastigogonus fossuliger is more consistently and more obviously green than other Amastigogonus species, but the green colour varies in intensity from individual to individual.