Ameritulla obscura, Bernard, Ernest C., 2016

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 : 458-461

Ameritulla obscura n. sp.

Figs 4 , 5A‒E

Material examined. Holotype female on slide, North Carolina, Swain County, Great Smoky Mountains National Park ( GSMNP), Ravensford area , leaf litter in mixed deciduous upland forest, near pitfall 35, N669200.106, E722181.572, 30 October 2001, E.C. Bernard and T. Goodrich, colls . Paratypes: three females on slides, four specimens in ethanol, same data as holotype; two females on slides, 9 in ethanol , same data as holotype except near pitfall 31, N669255.908, E722135.776; 17 specimens in ethanol , same data as holotype except floodplain forest near pitfalls 15 and 17, N 668461.484 E720196.354; two females on slides, five in ethanol, North Carolina, Swain County, GSMNP, Ravensford area , floodplain forest, near pitfall 13, N668491.940, E720265.304, 22 August 2001, P. Jennings & T. Goodrich, colls.; one female , Tennessee, Cumberland County, Obed Wild and Scenic River, Potters Ford , sandy soil on river bank, tall perennials, sample 7.186AF, 36° 04.372N, 84° 54.119W, elev. 213 m, 5 June 2007, A. Fjellberg, coll.

Description. White. Length of adult females 896‒1067 µm (n = 4, mean = 982 µm). Length ratio of Ant I:II:III:IV as 1:1.2:2.0:2.5. Pseudocellus shape Type III (crescentic) ( Figs 5A, B ), formula 11/111/11111. Pseudopores absent. Anal spines stout, curved, length about equal to that of hind unguis.

Granules on dorsum of head of medium size (diameter 2.0‒2.6 µm, mean 2.4 µm), evenly distributed, generally appearing round. Mid-dorsal region of body without longitudinal rows of granules. Granule diameter on Th. III 1.8‒2.1 µm (mean = 2.0 µm). Posterior region of all segments except pronotum and Abd. VI with 8‒12 distinct transverse rows of tightly packed granules ( Fig. 5D ). Granules on Abd. VI dense but not touching, not in rows; diameters of larger granules in anterior half 2.6‒3.6 µm (mean = 3.3 µm) ( Fig. 5D ).

Labial palpus with papillae A‒E, papilla spine A stout, rounded at tip; B‒E pointed ( Fig. 4 E). Guard setae 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. Mandible with four blunt apical teeth. Two stout, curved prelabral setae; labral seta formula 5-4-2, distal row and middle setae of middle row thicker and longer than other setae. Postantennal organ elongated, in deep trough, with two rows of oval vesicles, each with 18‒22 vesicles; PAO trough fused with fovea between setae sd3 and sd1 ( Fig. 4 D).

Ant. I with 7 setae, Ant. II with 11 setae. Sense organ of Ant. III with two largely exposed, converging sense clubs and two minute, weakly bilobed or trilobed sensory rods partially covered by cuticular lobes; three proximal guard setae ( Fig. 4 F). Ventral sense club stout, basal portion not offset. All Ant. III setae pointed ( Fig. 4 G). Dorsal side of Ant. IV with five arcuate sensilla; microsensillum rod-like, in shallow groove; subapical organite clavate, slightly bifid at tip, rising from cup-like depression; apical bulb spherical ( Fig. 4 F). Most longer dorsal and lateral setae of Ant. IV thin but sensilliform with blunt tips. Ventrally, Ant. IV with several sensilliform setae of various lengths; poorly defined ventral sensory field composed of mix of about nine short setae with finely rounded apices surrounding larger sensilliform seta ( Fig. 4 G).

All leg setae pointed. Trochanter with 4 setae, femur with 9 setae. Fore and middle tibiotarsi with 15 setae, A and B setal whorls with 8 and 7 setae, respectively ( Fig. 4 H); hind tibiotarsi with 14 setae in two whorls of 7 setae each ( Fig. 4 I). Unguis stout, without teeth or tunica-like expansion; unguiculus pointed, minute.

Dorsally, most cephalic setae of similar length, sd5, oc2, g3, p1 and p5 longer than others ( Fig. 4 A). Six setae between posterior cephalic pseudocelli, seta p1 about twice the length of p2. Two medial setae present anterior to a0. Seta v2 present, v1 absent. Pronotum with 8 setae. Mesonotum and metanotum each with m-row consisting of m1, m4 and m5; setae a2, a4, p3 and p5 macrosetae; p1 and p2 lengths subequal; microsensillum in shallow pit near long sensilliform seta. Abdominal segments I‒III lacking m-setae, setae a2, p3 and p5 longer than other setae. On Abd. IV seta p1 absent, m4 present, a2, a4, p3 and p5 long. Abd. V lacking seta p1; p2 slender, long, displaced far forward near a2, similar to p3, tip finely rounded; sensilliform seta p3 long, slender, tapering ( Fig. 5C ); a4 and p5 macrosetae. Abd. VI with two unpaired medial setae (m0, p0), without swellings or tubercles ( Fig. 4 B).

Pleural regions of Abd. I‒V with 2, 2, 2, 4, 0 setae, respectively; anterior sensilliform setae present on Abd. I‒IV ( Fig. 4 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 ( Fig. 4 C) typically with some asymmetry, especially on Abd. IV; ventral seta p5 on Abd. II‒IV and posterior setae of Abd. V sensilliform. Tenacular and furcal vestiges 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) ( Fig. 5E ).

Etymology. The type specimens were originally thought to be A. clavata and therefore were not differentiated for several years, thus obscura (L.)—dark, murky.

Remarks. Ameritulla obscura n. sp. is similar to A. clavata , but possesses seta m4 and lacks seta m2 on Abd. IV, and has a pair of pseudocelli on each body segment, whereas A. clavata lacks m4, possesses m2 and lacks pseudocelli on Th. I, Th. III, Abd. I and Abd. III. The new species can be separated from M. hades by the lack of seta p1 on Abd. IV and curved anal spines ( M. hades with seta p1 and straight anal spines).

Figures

FIGURE 4. Ameritulla obscura n. sp. A) Head, dorsal view. B) Thorax and abdomen, dorsal view. C) Abdominal segments II ‒ VI, ventral view. D) Postantennal organ. E) Labial palp. F) Third and fourth antennal segments, dorsal view. G) Fourth antennal segment, ventral view. H) Middle leg. I) Hind tibiotarsus. Scales: A, 100 µm; B, C, 100 µm; D ‒ I, 20 µm.

FIGURE 5. A ‒ E) Ameritulla obscura n. sp. A) Posterior cephalic pseudocellus. B) Pseudocellus of Abd. III. C) Setae in region of Abd. V pseudocellus. Note long setae have rounded tips, shorter setae have pointed tips. D) Abdominal segments VI and VI, dorsal view. E) Venter of Abd. VI. F) Mesaphorura yosii, venter of Abd. VI. Scales: A, B, 10 µm; C, F, 20 µm; D, E, 50 µm.