Tidesmus hastingsus Chamberlin 1941, new combination
Creators: name: Shear, William A.
name: Shelley, Rowland M.
Publisher: name: Zenodo
Year: 2007
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Diplopoda
Polydesmida
Tidesmus
Tidesmus hastingsus

description: Tidesmus hastingsus (Chamberlin, 1941), new combination
Brachydesmus hastingsus Chamberlin, 1941:27, figs. 48–49. Chamberlin & Hoffman, 1958:64.
Phreatodesmus hastingsus, Loomis, 1960:65. Buckett, 1964:12. Shelley, 1997:66 –67; 2002b:107. Hoffman, 1999:470.
Type specimen. The male holotype was collected by J. M. Linsdale, 20 February 1941, on the Hastings Reservation, Monterey Co., California. A vial labeled " Holotype " exists at the USNM, but the specimens inside bear no resemblance to the original description and illustration as discussed below. The holotype of B. hastingsus is therefore lost, and a definitive assessment of the species and its true generic assignment await collection of a topotypical male.
Remarks. Because of the difficult-to-interpret drawings of Chamberlin (1941) this species has been enigmatic for years. Having just examined extensive material of his new genera Phreatodesmus and Oodedesmus, Loomis (1960) gained insight into Chamberlin’s drawings and opined that hastingsus belonged in Phreatodesmus; however, he did not look at specimens. In an attempt to resolve the matter, Shelley (1997) examined the purported type material and found that it consisted of parts of individuals from at least two different polydesmids, one being an undescribed species and genus then known only from northern Idaho. He postulated that a previous worker had mixed these specimens with the actual type material, thus permanently confusing the situation.
We here add additional information based on a re-examination of these “ types.” The vial (USNM) contains no locality label and no original type-designation label in Chamberlin's style (with underlining in indelible red ink) at the time the species was described. Instead, only a newly inked, hand-written label reading “ Brachydesmus hastingsi Chamberlin [male] Holotype ” is in the vial that obviously was added rather recently, and whoever did so misspelled the species’ name. The vial contains three microvials, two of which contain even smaller microvials; their contents are as follows:
“Microvial 1” contains crushed and very fragmented segments of a small polydesmidan with acute paranotal corners and laterally serrate metazonites. The smaller, inner vial contains a single gonopod of a species of Speodesmus, probably S. bicornourus Causey, 1959 (Polydesmidae).
“Microvial 2” contains a male polydesmidan that lacks the head and first five segments. One gonopod is in situ, the other is in a smaller, inner microvial. The gonopods are from an undescribed species and genus that occurs in Latah Co., Idaho, more than 740 mi (1,180 km) to the northeast. It is highly unlikely that this species also occurs in Monterey Co., California.
“Microvial 3”contains the caudal ends of two specimens of this same undescribed genus and species, as indicated by the unique epiroct that expands into a distinct, distal knob.
Thus the “ type ” vial of Brachydesmus hastingsus contains nothing that can even tentatively be associated with this species as described and illustrated by Chamberlin (1941). The last person to examine this material prior to Shelley was Charles Withrow, then a graduate student at Ohio State University, whose unpublished doctoral research was a revision of Pseudopolydesmu s Attems, 1898 (Polydesmida: Polydesmidae) in eastern North America. In his unpublished thesis, Withrow also illustrated S. bicornourus and described the Idaho species as “ Idahodesmus dentatus," generic and specific names that are invalid because they were never published in accordance with the Code (Shelley 1996c). Thus all the components presently in the vial were studied at or about the same time by Withrow, and it seems likely that he is the source of the confusion that may have involved the destruction or misplacement of the true types of B. hastingsus. No wonder Shelley (1997) stated “…Chamberlin’s gonopod illustrations are among the worst in all his publications, and it is impossible to gain an impression of their structure from these drawings.” None of the gonopods in the vial are even remotely like those Chamberlin illustrated! However, having carefully studied Tidesmus gonopods, we now see what Loomis (1960) may have detected in Chamberlin’s rather cartoonish drawings, the deeply divided, U-shaped process B, the long, sinuate solenomere, the flattened, lobe-like distal zone, and even the transverse prefemur. We therefore agree with Loomis (1960) that hastingsus is referrable to Tidesmus (= Phreatodesmus). Assuming this to be correct, none of the somatic fragments in the vial seem part of the original specimen, as they lack the setiferous nodules and clavate setae typical of the genus. A male topotype is therefore imperative to determine if hastingsus is a distinct species of Tidesmus or a senior or junior synonym of a congener.
description: Published as part of Shear, William A. & Shelley, Rowland M., 2007, The milliped genus Tidesmus Chamberlin, 1943 (Polydesmida: Macrosternodesmidae), pp. 51-68 in Zootaxa 1656 on pages 61-63, DOI: 10.5281/zenodo.179846