Pygmarrhopalites youngsteadtii, Zeppelini, Douglas, Taylor, Steven J. & Slay, Michael E., 2009

Zeppelini, Douglas, Taylor, Steven J. & Slay, Michael E., 2009, Cave Pygmarrhopalites Vargovitsh, 2009 (Collembola, Symphypleona, Arrhopalitidae) in United States, Zootaxa 2204, pp. 1-18 : 8-10

Pygmarrhopalites youngsteadtii sp. nov.

pygmaeus -group s. str. ( Fig. 3 )

Description. Red pigment on and around eyes, one pair red spots on the posterior of head. Orange to red pigments scattered over anterior dorsal part of great abdomen. Dorsal body setae short on anterior part and about twice longer on posterior part of the great abdomen, posterior setae about same length as third unguis ( Table 2 ). Ant. IV of holotype 1.56 times cephalic diagonal, with 7 subsegments ( Fig. 3 A), apex with capitate sense rod. Ant. III not swollen basally; sense organ ( Fig. 3 B) with 2 parallel sense rods in single, shallow pit; seta Aai slightly curved and blunt; Api and Ape slender, bristle-like, shorter than Ae; Ap and Ai normal, elongate setae. 1+1 minute eyes present. Dorsal cephalic setae not spine-like, M4–5 absent, L1–2 absent ( Fig. 3 C). Metatrochanteral organ elongate ( Fig. 3 D). Seta FSa present on all tibiotarsi. First unguis elongated without inner tooth, second and third with inner tooth, tunica absent. All unguiculi with conspicuous corner tooth, first unguiculus slender, all unguiculi with short apical filament, not exceeding unguis tip ( Figs. 3 E). Corpus tenaculum with two setae ( Fig. 3 F). Dens with 7 dorsal E setae, E1 and E3 strongly spine-like, other E setae normal; L1–2 spine-like, L3 absent, 4 ventral setae rows (3,2,1,1) present, ve4 reduced ( Fig. 3 G), dental chaetotaxy in Table 3. Mucro narrow, gutter-like, with spoon shaped tip, both edges serrate. Anal valve without cuticular spines ( Fig. 3 H); setae C1, C2, C5 and C6 swollen basally, C3–4 lamellate, D5 present, D7 absent, chaetotaxy in Table 4 . Female subanal appendage slightly flattened on distal third, fringed at tip ( Fig. 3 I).

+= present in normal condition, -= absent, S= swollen basally, s= slightly swollen basally, L= lamellate, W= weakly lamellate, F= forked, B= branched at the base. Subanal appendage coding follows Christiansen (1966).

Type material. Holotype (female): USA, ARKANSAS, Newton Co., Tom Barnes Cave, 18-ii-05, N. Youngsteadt, J. Youngsteadt leg. ( INHS). Paratypes (2 adults females and 2 juveniles) in alcohol, same locality as holotype ( INHS).

Etymology. The specific epithet recognizes the many years of work by Norman and Jean Youngsteadt contributing to a greater understanding of cave biota in the Ozarks.

Remarks. Pygmarrhopalites youngsteadtii type specimens were found in a single cave, at Buffalo National River in the same physiographic province as P. leonardwoodensis and P. plethorasari , is close to the former based on anal valve setae C1, which is bifid in A. plethorasari . They can be differentiated by features in Table 4 . Despite of having a pair of eyes and pigments on the head and dorsum, this species presents some very typical cave features. The foot complex is highly troglomorphic, with very elongated unguis and short apical filaments, dens very slender (measurements in Table 2 ). This species is easily recognizable by a series of features. It presents a pair of pigment spots, like a false pair of eyes on the posterior part of the head, a fourth antennal segment 7-subdivided, and a tiny ve4 seta on the ventral surface of dens, very displaced towards the base of the dens.

Figures

FIGURE 3. Pygmarrhopalites youngsteadtii sp. nov.: A, Fourth antennal segment; B, Apical sensory organ of the third antennal segment; C, Posterior dorsal cephalic chaetotaxy; D, Metatrochanteral organ; E, Empodial complex (a –– first leg, b –– second leg, c –– third leg); F, Tenaculum; G, Dorsal and ventral chaetotaxy of the dens; H, Chaetotaxy of the anal valve; I, Subanal appendage of the female.

Tables

TABLE 4. Anal valve chaetotaxy of the six new species of Pygmarrhopalites.

Species	C1	C2	C3	C4	C5	C6	C7	C8	D5	D7	E8	E9	E10	B10	Anal valve spines
P. ashcraftensis	+	+	+	+	+	+	+	+	+	-	+	-	+	D5	-
P. leonardwoodensis	s	S	W	W	L	LB	+	S	+	-	+	+	+	C15	-
P. buffaloensis	+	s	S	S	S	S	+	+	-	+	+	+	+	B5	-
P. youngsteadtii	s	s	W	W	S	S	+	+	+	-	+	-	+	C10	-
P. plethorasari	F	s	L	LB	L	L	+	S	+	+	+	+	+	BC10	-
P. shoshoneiensis	F	+	s	s	S	S	+	+	-	-	+	-	+	E2	-