Marek, Paul E., Means, Jackson C. & Hennen, Derek A., 2018, Apheloria polychroma, a new species of millipede from the Cumberland Mountains (Polydesmida: Xystodesmidae), Zootaxa 4375 (3), pp. 409-425: 416-420
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Apheloria polychroma , new species
Apheloria “flavissima” ( Hobson 2010),
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) from Virginia, Lee County, The Cedars, CR-738 (36.65624°N, - 83.20165°W, Elev. 436 m), 28 September 2006, 16:00 (Colls: P. and B. Marek). Non-type material examined listed in Table 1.GoogleMaps
Diagnosis. Adult males of A. polychroma are distinct from other apheloriine species based on the following combination of characters: Color. Tergites usually with 4 yellow spots (i.e. 1 metatergal, 1 prozonal, 2 paranotal spots, Figs 2A –F, M –PView FIGURE 2). Collum usually uniformly yellow (1.25Y 7/14). Jet-black background (N 0.5–0.75). Gonopods. Gonopodal acropodite smoothly circular, O-shaped ( Figs 3A, BView FIGURE 3)—without elbow as in A. tigana ( Fig. 4CView FIGURE 4, arrow). Acropodite narrow, half width of tibia on leg pair 9, of uniform width throughout. Acropodite gradually tapered to curved acuminate J-shaped apex, not L-shaped and abruptly twisted as in A. montana , A. tigana , A. virginiensis corrugata ( Figs 3CView FIGURE 3; 4B, D, F). Acropodite shaft without cingulum (midlength transverse groove) or preapical teeth or projections as in Brachoria . Prefemur with a thin sharp prefemoral process, one-ninth length of acropodite ( Fig. 3AView FIGURE 3, arrow), not long and scythe-like as in A. montana , A. tigana , A. virginiensis corrugata ( Figs 4B, D, FView FIGURE 4).
Note: The 4-spotted yellow color morph with a uniformly yellow collum unambiguously diagnoses A. polychroma ( Fig. 2A, C, EView FIGURE 2). However, there are at least 6 color morphs of the species with a substantial continuum of hues and patterns among them ( Figs 2View FIGURE 2, 5View FIGURE 5). There are frequently several color morphs of the species at a single locality, and as color varies considerably, it should be used with caution as a diagnostic character for this species.
Description. Based on Holotype (♂) FMNH-INS 60792.
Measurements: BL = 48.70, CW = 7.50, IW = 4.10, ISW = 1.00, B11W = 9.50, B11H = 5.40.
Head: Antennae extending posteriorly to anterior margin of 3rd tergite, relative antennomere lengths 2>5>3>4>6>1>7. Antennae with 4 sensillum types, sensillum shafts smooth without barbules. Four apical cones ( AS) in square cluster on 7th antennomere. Chaetiform sensilla (CS) on antennomeres 5–7. Antennomeres 1–4 smooth with sparse vestiture of CS. Trichoid sensilla (TS) on antennomeres 1–7, coronally encircling apex. Spiniform basiconic sensilla (Bs2) in clusters of 15 on apical dorsal (retrolateral) surface of antennomeres 5, 6; Bs2 shaft 1/10 length of CS.
Tergites: Collum with straight cephalic edge, abruptly tapering laterally. Collum with carina present on anterolateral margins, absent medially. Caudolateral corners of paranota rounded cephalically on body rings 1–4; acute, projecting caudally on body rings 5–19. Caudolateral corners of paranota 7–19 with small posteriorprojecting nubbin. Paranota dorsal surface loosely wrinkled, appearing leathery. Ozopores oriented dorsolaterally. Pore formula normal: 5, 7, 9, 10, 12, 13, 15–19. Paranota with anterodorsal region scooped out. Gonapophyses cylindrical apically. Pleural tubercle absent, with slight swelling between paranotal base and spiracle. Sterna without posteriorly projecting spines, with slightly curved caudal margin. Sterna 2–11 sparsely setose (ca. 10 setae), sterna 12–18 lacking setae, ventral surface smooth.
Gonopods: In situ configuration—Acropodite base projected posteroventrally, curved anteromedially in smooth O-shaped form ( Fig. 3A, BView FIGURE 3). Terminal arc of acropodite oriented ventrolaterally. O-shaped arc nearly closed, gap 1/8 length of circumference between prefemoral process and apex ( Fig. 3A, BView FIGURE 3). Right, left acropodites crossed midlength, appearing intertwined. Gonocoxae with conical protuberance apically, telopodites arising subapically. Telopodites—Prefemur with thin sharp prefemoral process, one-ninth length of acropodite, with apex tapered to sharp curved point, sickle-shaped, width at base 1/4 its length ( Fig. 3AView FIGURE 3, arrow). Acropodite bent 90° posteriorly at prefemur ( Fig. 3CView FIGURE 3, arrow), prostatic groove arcs 90° from cannula to acropodite base ( Fig. 3BView FIGURE 3, arrows). Gonopodal acropodite narrow, half width of tibia on leg pair 9, tapered to curved acuminate apex. Acropodite with ventrobasal surface facing anterolaterally. Acropodite base without spines on dorsal surface. Acropodal basal and apical ventral surfaces not coplanar, apical surface facing ventrolaterally; anterior twist absent ( Fig. 3CView FIGURE 3). Acropodal ventral surface flat, not swollen, smooth. Acropodite without midlength transverse groove, or cingulum. Acropodite shaft of uniform width, tapered to acuminate apex distal to region with setae. Acropodite elliptical in cross-section, tapered acuminate apex thinner, transparent. Acropodite margin rounded, lacking sharp edge; marginal teeth absent. Apical 1/9 of acropodite recurved, J-shaped, projecting cephalically ( Fig. 3CView FIGURE 3). Acropodite region with setae about 1/3 its total length ( Fig. 3BView FIGURE 3).
Paratype (♀) FMNH-INS71228—Measurements: BL = 50.30, CW = 8.00, IW = 4.80, ISW = 1.40, B10W = 11.81, B10H = 7.10.
Cyphopods: Cyphopod receptacle (at its greatest breadth) equal in width to prefemur length. Receptacle heartshaped, pointed end facing medially. Cyphopodal valves symmetric, anterior valve slightly more convex. Cyphopods with valvular suture facing laterally, without midlength ramp-like swell.
Variation. Apheloria polychroma is known from the Cumberland Mountain Thrust Block region at the confluence of southwestern Virginia, northeastern Tennessee, and southeastern Kentucky ( Fig. 6View FIGURE 6). There are at least six color morphs with substantial variation in coloration between them: (1) four-spotted, with yellow to orange paranotal, metatergal, prozonal and collum spots, and legs and collum often completely yellow and sometimes with red legs ( Figs 2A –F, M –OView FIGURE 2); (2) striped, with yellow metatergal, paranotal, anterior collum stripes, and legs ( Figs 2G, HView FIGURE 2); (3) three-spotted, with creamy white paranotal, metatergal and collum spots, and red legs ( Figs 2I, JView FIGURE 2); (4) three-spotted, with yellow paranotal, metatergal and collum spots, and red or yellow legs ( Figs 2K, LView FIGURE 2; 5A, B); (5) striped/four-spotted mix, superimposition of striped and four-spotted yellow morphs ( Figs 2M, NView FIGURE 2); and (6) twospotted, with yellow paranotal spots, and red or yellow legs ( Figs 2Q –TView FIGURE 2). Some three-spotted yellow individuals possess faint metatergal spots, appearing nearly two-spotted ( Fig. 2SView FIGURE 2). The dorsal color of A. polychroma is always yellow and black; however, the pattern varies from two, three, or four maculae, to metatergal stripes. The hue consists of variations of yellow: from light cream-white to brilliantly saturated yellow. Based on the molecular phylogeny of populations of A. polychroma ( Fig. 1View FIGURE1), some individuals that share a uniform mitochondrial 16S sequence possess three distinct color morphs (morphs 1, 2 and 5 from above). The color morphs lack phylogenetic conservation, whereby individuals sharing the same aposematic appearance are not monophyletic ( Fig. 1View FIGURE1). Evolutionary shifts between colors, based on reconstructing color morphs on a phylogeny using parsimony, occurred frequently with ca. 29 changes ( Fig. 1View FIGURE1). Brachoria dentata Keeton, 1959 mimics A. polychroma in color and pattern at six of the seven localities where they were found to co-occur. The other five species of Brachoria cooccur at fewer localities. There is typical sexual size dimorphism between males and females, and negligible variation of measurements within sex. Measurements: ♂ (n = 10) BL = 37.80–49.45 (45.68/3.45). CW = 6.90–8.80 (7.58/0.63). IW = 4.10–5.00 (4.63/0.30). ISW = 1.00–1.40 (1.20/0.13). B10W = 8.80–10.79 (10.11/0.82). B10H = 4.60–6.10 (5.66/0.65). ♀ (n = 7) BL = 41.60–50.30 (46.67/3.07). CW = 6.60–8.30 (7.63/0.59). IW = 4.70–5.40 (5.01/0.29). ISW = 1.20–1.40 (1.31/0.09). B10W = 9.10–11.81 (10.64/0.96). B10H = 6.10–7.10 (6.4/0.37).
Ecology. Apheloria polychroma individuals were collected in mesic broadleaf deciduous forests and occasionally in more xeric glades, for example 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 encountered beneath decomposing leaves and walking atop detritus on the forest floor. Individuals of A. polychroma were more often exposed to view than other apheloriines, bolder in behavior, and were more likely to thrash when disturbed. When handled, individuals would emit copious amounts of defense secretions. Due to similarity in color patterns and overlap in distribution, A. polychroma may be confused in the field with six species of Brachoria , which include Brachoria dentata Keeton, 1959 ; Brachoria cedra Keeton, 1959 ; Brachoria hoffmani Keeton, 1959 ; Brachoria insolita Keeton, 1959 ; Brachoria mendota Keeton, 1959 ; and Brachoria sheari Marek, 2010 . Mimetic resemblance between individuals of A. polychroma and B. mendota at Natural Tunnel State Park (Scott County, Virginia) is one of the most accurate in the mimicry system ( Fig. 5View FIGURE 5). Apheloria polychroma can be distinguished from these taxa in the gonopod morphology, e.g. by the absence of a cingulum, or a midlength transverse groove on the acropodite, and presence of an O-shaped telopodite ( Fig. 3A, BView FIGURE 3).
Distribution. Known from southwestern Virginia (Lee, Scott, Norton, and Wise Counties), southeastern Kentucky (Bell and Harlan Counties), and northeastern Tennessee (Campbell, Claiborne, and Hancock Counties, Fig. 6View FIGURE 6). The distribution of A. polychroma is coincident with the boundaries of the High Knob Landform, and more broadly the Cumberland Mountain Thrust Block ( Rich 1934; Browning 2009).
Notes. Apheloria polychroma was previously known by the informal names Apheloria “ flavissima ” ( Hobson, 2010), Apheloria “Stone” ( Marek & Bond 2007; Means & Marek 2017), and Apheloria “Clade A” ( Marek & Bond 2009).
Etymology. This species is named for its extremely variable coloration. The specific name is a noun in apposition derived from the Greek polu-, ‘many’, and khrōma, ‘color’.
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