Ameritulla clavata ( Mills, 1934 ) Mills, 1934

Bernard, Ernest C., 2016, Two new genera and five new species of Tullbergiidae (Collembola) from the southern Appalachian Mountains of North America, with redescription of Tullbergia clavata Mills, Zootaxa 4162 (3), pp. 451-478 : 454-458

Ameritulla clavata ( Mills, 1934) new combination

Figs 1 , 2 , 3A, B

Tullbergia clavata Mills, 1934:38 ; Waltz & Hart, 1995:115 (males). Mesaphorura clavata Bagnall, 1947:444 ; Dunger & Schlitt, 2011:49.

Material examined. Four cotypes examined: cotype female designated as lectotype, Ames , Iowa, 2 April 1932, INHS slide number 529.347, H.B. Mills, coll. ; paralectotype female and paralectotype juvenile, Ames , Iowa, 3 April 1932, slides 529.345, 529.346, H.B. Mills, coll. ; paralectotype female, Traer, Indiana, 5 November 1931, slide 529.348, H.M. Harris, coll. Additional specimens examined, all in University of Tennessee Entomology Collection: one female, Tennessee, Sequatchie County, Whitwell , Kimmons Farm “ Moonshadow ”, to right of cave mouth, 15 May 1997, sample 1997-37, E.C. Bernard & P.L. Jennings, colls.; one female, North Carolina, Swain County , GRSM, Lost Cove Trail , leaf litter, 35°29.449’N 83°48.099’W, 8 May 2004, sample 2004-11 WMM, W.M. Merrit, coll.; two females, North Carolina, Swain County , GRSM, culvert along Tow String Road, among liverworts, 27 October 2004, E.C. Bernard & A. Mayor, colls.; one female, North Carolina, Swain County , GRSM, Newfound Gap, 22 June 2005, sample RTA-05-028, R.T. Allen, S.M. Allen & H.S. Allen, colls.; six females, North Carolina, Haywood County , GRSM, Purchase Knob, leaf litter in heavy rhododendron thicket, 24 May 2007, sample AHSLC 07024 EB, E.C. Bernard, coll.

Redescription. White. Length of three adults labeled as cotypes 921‒1137 µm, length of eight additional adults 895‒1204 µm (mean of 11 specimens = 1014 µm). Length ratio of Ant. I:II:III:IV approximately 1:1.1:1.6:2.2. Pseudocellus shape Type III (crescentic) ( Fig. 2 B), formula 11/010/01011. Pseudopores absent. Anal spines stout, slightly curved, about 1.5× longer than hind unguis.

Granules on dorsum of head of small to medium size (diameter 1.4‒2.3 µm, mean = 2.0 µm), evenly distributed, appearing round or broadly oval. Diameter of Th. III granules 1.3‒2.0 µm, mean = 1.6 µm. Distinct mid-dorsal longitudinal rows of granules not present. Posterior region of all segments except pronotum and Abd. VI with 8‒12 transverse rows of tightly packed granules (Figs 3A, B). Granules of Abd. VI not in distinct rows, diameter 1.4‒2.1 µm (mean = 1.6 µm) (Figs 3A, B).

Labial palpus ( Fig. 1 H) with papillae A‒E, papilla spine A stout, rounded at tip; B‒E pointed. Eight guard setae present: a1 and b1 minute, papilliform, papilla B with one additional guard seta, papilla D with two guards, papilla E with three. Maxillary palpus with one sublobal hair, spine of papilla slightly longer than basal seta ( Fig. 1 I). Mandible with four blunt apical teeth ( Fig. 1 J). Prelabral setae two, stout, curved; labrum with 11 setae in three rows (5-4-2), setae of distal pair and middle setae of middle row stronger and longer than other labral setae ( Fig. 1 E). Postantennal organ elongated, in deep trough, with two rows of oval vesicles, each with 18‒22 vesicles ( Fig. 2 A). Trough of PAO closed at medial end by one or more granules, not extending to fovea between setae sd1 and sd3.

Ant. I with 7 setae, Ant. II with 11 setae. Sense organ of Ant. III ( Fig. 1 F) with two exposed, converging sense clubs and two minute, weakly bilobed or trilobed sensory rods partially covered by prominent cuticular lobe; three proximal guard setae. Ventral sense club stout; all Ant. III setae pointed ( Fig. 1 G). Dorsal side of Ant. IV with five arcuate sensilla; microsensillum rod-like, in shallow groove; subapical organite clavate, extending from cup-like depression; apical bulb spherical ( Fig. 1 F). Most longer dorsal and lateral setae of Ant. IV thin but sensilliform with blunt tips, only one pointed seta mid-dorsally. Ventrally, Ant. IV with several sensilliform setae of various lengths; ventral sensory field not defined, short setae a mix of ordinary and thin sensilliform setae with finely rounded apices surrounding larger sensilliform seta ( Fig. 1 G).

All leg setae pointed. Trochanter with 4 setae, femur with 10 setae. Fore and middle tibiotarsi with 15 setae, A and B setal whorls with 7 and 8 setae, respectively; hind tibiotarsus with 14 setae. Unguis stout, without teeth or tunica-like expansion; unguiculus pointed, minute ( Fig. 1 K).

Dorsally, most cephalic setae of similar length, sd5, oc2, g3 and p5 longer than others ( Fig. 1 A). Six setae between posterior cephalic pseudocelli, seta p1 about 1.5× the length of p2. Two medial setae present anterior to a0. Seta v2 present, v1 absent. Pronotum with 8 setae. Mesonotum and metanotum ( Fig. 1 B) each with m-row consisting of m1, m4 and m5; setae a2, a4 and p5 macrosetae; p3 longer than p4 but shorter than p5; p1 and p2 lengths equal; microsensillum in shallow pit near long sensilliform seta. On Abd. I‒V seta p3 distinctly sensilliform. Abd. I‒III lacking m-setae, setae a2 and p5 longer than other setae. On Abd. IV setae a2, a4 and p5 long; small m2-seta present. Abd. V lacking seta p1; p2 long, displaced far forward near a2; a4 and p5 macrosetae. Abd. VI with two unpaired medial setae (m0, p0), without swellings or tubercles.

Pleural regions of Abd. I‒V with 1, 2, 2, 6, 1 setae, respectively; sensilliform setae present on Abd. II‒IV, anteriorly inserted on Abd. II and III, posteriorly inserted on Abd. IV ( Fig. 1 B).

Ventrally, head with three pairs of medial setae. Mesosternum and metasternum each with two setae. Ventral tube with 4+4 setae on valves and 2+2 setae on base. Ventral abdominal setae typically with some asymmetry, especially on Abd. IV ( Fig. 1 C). Ventral setae p2 and p5 on Abd. II, p5 on Abd. III and IV, and posterior setae of Abd. V sensilliform. Remnant tenacular and furcal regions absent on Abd. IV and V. Sternum of Abd. V with six setae surrounding the genital aperture and two microsetae on the anterior lip; Abd. VI sternum with full complement of setae (a1‒5, m2‒5, p1‒5, va1‒3) ( Figs 1 D, 2C).

Remarks. Ameritulla clavata n. comb. is easily recognized as the only large North American tullbergiid with pseudocelli absent from both Th. I and Th. III. The only other tullbergiids with this arrangement are the smaller Mixturatulla ozwini n. gen., n. sp. and Psammophorura miniclavata n. sp. Oddly, P. miniclavata n. sp. and A. clavata n. comb. have the same pseudocellar formula (11/010/01011). The constant presence of seta m2 on Abd. IV is a distinctive character and may be unique in this family. Ameritulla obscura n. sp. (below) has one pair of pseudocelli on Th. II‒III and Abd. I‒V.

Waltz & Hart (1995) reported on the presence of males in two Indiana locations and minor variability in the lengths of some setae, but ascribed setal differences to intraspecies variation.

Figures

FIGURE 1. Ameritulla clavata n. comb., lectotype female unless otherwise noted. A) Head, dorsal view. B) Thorax and abdomen, dorsal chaetotaxy. C) Abdominal segments II ‒ V, ventral chaetotaxy, specimen from Great Smoky Mountains National Park (GRSM). D) Venter of Abd. VI, specimen from GRSM. E) Labrum. F) Third and fourth antennal segments, dorsal view. G) Fourth antennal segment, ventral view. H) Labial palpus. I) Outer lobe of maxilla. J) Apex of mandible. K) Middle femur and tibiotarsus, ventral view. Scales: A, 50 µm; B, C, 50 µm; D, H, I, 20 µm; E, 20 µm; F, G, H, K, 20 µm.

FIGURE 2. Ameritulla clavata n. comb. A) Postantennal organ, lectotype. B) Anterior cephalic pseudocellus, Sequatchie Co., Tennessee, specimen. C) Ventral chaetotaxy of Abd. VI, Haywood Co., North Carolina, specimen. Scales: A, B, 10 µm; C, 50 µm.