Narceus Rafinesque, 1820

Shelley, Rowland M. & Floyd, Samuel D., 2014, Expanded concept of the milliped family Spirobolidae Diplopoda: Spirobolida: Spirobolidea): Proposals of Aztecolini n. tribe and Floridobolinae / ini and Tylobolini n. stats.; (re) descriptions of Floridobolus and F. penneri, both Causey, 1957, and F. orini n. sp.; hypotheses on origins and affinities, Insecta Mundi 2014 (357), pp. 1-50 : 29-30

Genus Narceus Rafinesque, 1820

Narceus Rafinesque, 1820:8 . Hoffman and Crabill, 1953:80. Causey, 1955a:70–71. Hoffman, 1957:68; 1980a:77; 1999:38–39. Chamberlin and Hoffman, 1958:165. Hoffman and Keeton, 1960a:17. Keeton, 1960b:62–66. Jeekel, 1971:201 Shelley, 2000a:184 ; 2001a:244. Kevan, 1983:2962.

Rhexenor Rafinesque, 1820:8 . Hoffman and Crabill, 1953:81. Causey, 1955a:70. Hoffman and Keeton, 1960a:20. Jeekel, 1971:204.

Spirobolus (not Brandt): Newport, 1844:269. Wood, 1865:207. Bollman, 1887:28; 1893:118. Brölemann, 1914:2. Williams and Hefner, 1928:123. Chamberlin, 1947:44–46.

Arctobolus Cook, 1904:64 . Hoffman and Keeton, 1960:8. Jeekel, 1971:192.

Type-species. Of Narceus , N. tinctorius Rafinesque, 1820 , by monotypy; of Rhexenor , R. annularis Rafinesque, 1820 , by monotypy; of Arctobolus , A. onondaga Cook, 1904 , by original designation.

Diagnosis. Posterior gonopod prefemoral process long and subdactyliform, bulbous basally with distal part strongly prolonged, extending for at least 2/3 of length of acropodite, deeply recessed within and partly enclosed by latter.

Components. Four nominal species: N. americanus (Beauvois, 1817) , N. annularis ( Rafinesque, 1820) , N. gordanus (Chamberlin, 1943) , and N. woodruffi Causey, 1959 ( Causey 1959; Keeton 1960a; Shelley 2002c , 2006; Shelley et al. 2006).

Distribution ( Fig. 30 ). One of the four most widely distributed North American chilognath genera, along with Oriulus and Aniulus ( Julida : Parajulidae ) and Underwoodia ( Chordeumatida : Caseyidae ) ( Shelley 1992 , 2001b, 2002d), Narceus is the most commonly encountered diplopod genus in eastern North America. It is ubiquitous within its range and blankets the eastern familial/subfamilial/tribal areas except for southernmost peninsular Florida and the Keys, inhabited by Aztecolini / Chicobolus / C. spinigerus . Though erroneously including this southernmost area, Shelley et al. (2006) detailed its distribution.

Origin. From the Mexican source area, ancestral spirobolinine stock spread northward across the breadth of the “proto-southern US,” and the faunal continuity was broken by the Western Interior Seaway sometime during the Cretaceous. We can never know when the last thread of genetic continuity was severed, but we consider this the date when Narceus and Spirobolus simultaneously arose. We therefore arbitrarily select <290 mya as the date of origin of both taxa.

Remarks. Per present concepts, particularly that of Keeton (1960a), Narceus comprises four species not three (see components section above), including the often overlooked N. woodruf fi Causey, 1959. It and N. gordanus are known only from peninsular Florida and are therefore considered endemics until authentic adult males are discovered elsewhere ( Shelley and Bauer 1997, Shelley et al. 2006). The records of N. gordanus from Charleston Co., South Carolina, and Carter Co., Tennessee, are misidentifi- cations of N. americanus / annularis and are based entirely on females. Consequently, Shelley and Bauer (1997, footnote 2) deleted N. gordanus from both states and implied endemicity to peninsular Florida by noting that the only authentic records are from Alachua and St. Johns cos., southward; subsequently, Shelley et al. (2006) stated this outright. Hoffman (1999) overlooked Shelley and Bauer’s footnote and mistakenly reported, “the apparently disjunct record for Charleston, South Carolina, requires verifi- cation.” Known only from Alachua, Columbia, and Putnam cos., N. woodruffi has been overlooked in five works (Hoffman 1980 [by implication], 1999; Shelley and Bauer 1997; Shelley 2001a ; Walker et al. 2009) and reported in five ( Causey 1959; Keeton 1960a; Shelley 2002c , 2006; Shelley et al. 2006). Proposed by Causey (1959) for an adult male holotype and two female paratypes from Putnam Co., N. woodruffi missed inclusion in the first checklist ( Chamberlin and Hoffman 1958) by one year as it also did the familial revision, then in press. Consequently, Keeton (1960a) could only acknowledge its existence, stating in footnote 4, p. 65, that he had not seen the types and would not evaluate the name. Although the holotype was lost, Shelley (2002c) redescribed N. woodruffi from the female paratypes and four samples with males (FSCA); four years later, he ( Shelley 2006 ) reported the holotype after it was discovered in the general AMNH holdings. Narceus woodruffi is the smallest-bodied spirobolid and the second smallest North American spirobolidan behind southwestern arinolinine atopetholids. From the standpoint of body size, N. woodruffi more closely resembles a spirobolellid or large-bodied representative of Parajulidae (Julida) , like a species of Bollmaniulus Verhoeff, 1926 , along the Pacific Coast. Somatically and gonopodally, N. woodruffi is a unique spirobolid that appears to constitute a distinct clade, so its omission from the molecularly-based generic analysis ( Walker et al. 2009) seems one that could impact results/conclusions and hence necessitate redoing aspects of this work.

Figures

Figure 30. Distribution of Spirobolini/Narceus plotted against Cretaceous land patterns; submerged, marine Florida terrane and approximate maximal dimensions of the Western Interior Seaway in light blue. Ap, Appalachia. L, Laramidia.