Apheloria polychroma Marek, Means & Hennen, 2018

Apheloria polychroma Marek, Means & Hennen, 2018 View in CoL

Vernacular name: “The colorful cherry millipede”

Figs 8, 14

Apheloria polychroma Marek, Means & Hennen, 2018: 416 View in CoL View Cited Treatment .

Apheloria roanea Chamberlin, 1947: 26 View in CoL . Synonymized by Hoffman, 1999: 306.

Detailed taxonomic history in Appendix 1.

Material examined: Type specimens— ♂ holotype ( FMNH-INS60792 ), 1 ♀ paratype ( FMNH-INS71228 ), 3 ♂, 3 ♀ paratypes ( VTEC, MMC0309 , 310 , 313 , 305 , 306 , 308 ), 1 ♂, 1 ♀ paratypes ( VMNH, MMC0314 , 312 View Materials ) from Virginia, Lee County , The Cedars , The Cedars State Natural Area Preserve, CR-738 ( 36.65624°N, - 83.20165°W, Elev. 436 m), 28 September 2006, 16:00 ( Colls: P. and B. Marek) ( vidi). Non type material examined in Appendix 2. Materials examined are archived in the Virginia Tech Data Repository at: https://doi.org/10.7294/29829209 GoogleMaps

Diagnosis: Apheloria polychroma is distinct from other apheloriine species based on the following combination of characters: Color. Tergites usually with 4 yellow spots on a jet black background: 1 metatergal, 1 prozonal, 2 paranotal spots ( Fig. 14). Collum usually uniformly covered in yellow ( Fig. 10). ♂ Gonopods. Gonopodal acropodite smoothly circular, O-shaped ( Fig. 8A)—without elbow as in A. virginiensis ( Fig. 7A, elb). Not smoothly oval-shaped, 0-shaped, as in Rudiloria . Acropodite narrow, one-half width of tibia on leg pair 9; of uniform width throughout.Acropodite gradually tapered to curved acuminate, J-shaped apex ( Fig. 8B)—not L-shaped and abruptly twisted as in A. corrugata , A. virginiensis , A. montana ( Figs 4B, 7B, 13B). Acropodite shaft without cingulum nor preapical teeth nor projections as in Appalachioria , Brachoria . Prefemur with a shorter, scythe-like prefemoral process, one-ninth length of acropodite ( Fig. 8A, pfp)—not long and scythe-like as in A. corrugata , A. virginiensis , A. montana ( Figs 4A, 7A, 13A). With acute angle at prefemur-acropodite junction ( Fig. 8B), not with distinct bend tubercle at junction as in A. corrugata , A. virginiensis , A. montana ( Figs 4B, 7B, 13B, bt).

Note about coloration: When it is present, the 4-spotted yellow color morph with a collum that is uniformly covered in yellow unequivocally diagnoses A. polychroma from all other species of Xystodesmidae ( Fig. 14). However, this morph is geographically restricted to the Powell River Valley from Big Stone Gap, Virginia, in the north and Norris, Tennessee in the south. There are no fewer than six distinct color morphs of the species with a continuum of hues and patterns between them (“ Figs 2A – T, 5 ” in Marek et al. 2018). There are often multiple color morphs of the species that are syntopic and co-occur in a small area (≥ 10 m 2). Because color varies considerably intraspecifically, it should be cautiously used as a diagnostic character for this species.

Variation. There are at least six color morphs of Apheloria polychroma with a continuum of coloration between them: (1) four-spotted, with yellow to orange paranotal, metatergal, prozonal and collum spots, and legs (collum often uniformly covered in yellow, Fig. 14) and sometimes with red legs; (2) striped, with yellow metatergal— paranotal stripes, anterior collum stripe, and legs (“ Figs 2G, H ” in Marek et al. 2018); (3) three-spotted, with creamwhite paranotal, metatergal and collum spots, and red legs (“ Figs 2I, J ” in Marek et al. 2018); (4) three-spotted, with yellow paranotal, metatergal and collum spots, and yellow or red legs (“ Figs 2K, L; 5A, B ” in Marek et al. 2018); (5) striped/four-spotted superimposition of striped and four-spotted yellow morphs (“ Figs 2M, N ” in Marek et al. 2018); and (6) two-spotted, with yellow paranotal spots, and yellow or red legs (“ Figs 2Q – T ” in Marek et al. 2018). Some three-spotted yellow individuals have faint metatergal spots and appear nearly two-spotted (“ Fig. 2S ” in Marek et al. 2018). The dorsal color of A. polychroma is always yellow to red and jet black; however, the pattern varies from two, three, or four spots, to metatergal stripes, and superimposition of the latter two patterns.

There is typical sexual size dimorphism between males and females, where females are larger, and negligible variation of measurements within individuals of the same sex. Somatic measurements: ♂ (n = 13) BL = 39.59–58.52 (50.24/6.18). CW = 6.76–9.22 (7.69/ 0.69). IW = 4.19–5.21 (4.78/0.28). ISW = 1.10–1.72 (1.27/0.18). B10W = 9.29–12.47 (10.43/0.81). ♀ (n = 10) BL = 37.78–53.47 (44.36/5.78). CW = 6.75–8.62 (7.66/0.53). IW = 4.61–5.69 (5.09/0.32). ISW = 1.20–1.52 (1.34/0.10). B10W = 8.90–12.70 (10.61/1.09).

Ecology. Apheloria polychroma individuals were typically encountered in mesic habitats such as broadleaf deciduous forests, and seldom in more xeric habitats such as glades—for example in The Cedars Natural Area Preserve in Lee County, Virginia that consists of karst overlain with a mixed deciduous and eastern red cedar forest ( Juniperus virginiana L.). Individuals were normally found beneath decomposing leaves and occasionally walking atop detritus on the forest floor. These individuals were more often exposed to view than others of the family, bolder in behavior, and were more likely to writhe and flail when disturbed—compared to coiling into a ball like others. When handled, individuals would emit copious amounts of defense secretions and liquid feces.

Due to mimicry in color and overlap in distribution, A. polychroma may be confused in the field with A. corrugata , A. montana , Appalachioria eutypa ( Chamberlin, 1939) ; C. georgiana (Bollman, 1889) ; P. flavipes ; and eight species of Brachoria : Brachoria cedra Keeton, 1959 ; Brachoria dentata Keeton, 1959 ; Brachoria hansonia Causey, 1950 ; Brachoria hoffmani Keeton, 1959 ; Brachoria insolita Keeton, 1959 ; Brachoria mendota Keeton, 1959 ; Brachoria sheari Marek, 2010 ; Brachoria splendida ( Causey, 1942) . Mimetic resemblance between A. polychroma and B. mendota at Natural Tunnel State Park (Scott Co., Virginia) is one of the most accurate in the millipede mimicry system ( Marek & Bond 2009, Marek et al. 2018). The Pennington Gap mimic millipede, Brachoria dentata Keeton, 1959 , mimics A. polychroma in color morph at six of the seven localities where they were found to co-occur. Five other species of Brachoria co-occur with A. polychroma at fewer localities. When syntopic with A. polychroma , though rare, some individuals of the species B. cedra , B. dentata , B. mendota , and B. sheari can have 4 yellow spots, including the distinctive prozonal spot, and appear almost indistinguishable from A. polychroma . However, these Brachoria species never possess a collum that is uniformly covered in yellow. Apheloria polychroma can be distinguished from other species of Apheloria by its diagnosis, and from Appalachioria , Brachoria , Cherokia , and Pleuroloma species by gonopod morphology, specifically by the absence of a cingulum, or a mid-length transverse groove on the acropodite, and the presence of a circular acropodite ( Fig. 8A).

Distribution. Known from the mountains between southwestern Virginia, southeastern Kentucky, eastern Tennessee, and northwestern Georgia ( Fig. 11). Not known to occur in North Carolina. The greatest diversity in coloration of A. polychroma is seen in southwestern Virginia where the taxon is syntopic with six species of the genus Brachoria .