Psammophorura miniclavata, 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 : 464-467

Psammophorura miniclavata n. sp.

Figs 8 , 9

Material examined. Holotype female (slide) and 36 paratypes (7 females on slides, remainder in ethanol), Tennessee, Sullivan County, Cherokee National Forest, Jacob Creek riparian zone, 36.5788 -81.9861, elev. 487 m, moist moss mat in Rhododendron catawbiense - Tsuga canadensis stand, sample 2008-3B, 11 June 2008, E. C. Bernard & K.- H. Park, colls.

Description. White. Length of adult females 552‒611 µm (n = 6, mean = 580 µm). Antenna length (62‒65 µm) shorter than head length (87‒93 µm), length ratio of Ant I:II:III:IV as 1:1.5:1.9:2.0. Pseudocellus shape primarily Type I (stellate) (Fig. 9B), a few grading toward Type II (double striate), formula 11/010/01011. Pseudopores absent. Anal spines two, curved, pointed, on short, broad bases.

Granules on head and body small, composed mainly of three elements and appearing triangular. Thoracic nota and Abd. I mid-dorsally with 2‒4 longitudinal rows of granules (Fig. 9A); pronotum primarily with uniform, dense granules. On Th. II, Th. III and Abd. I adjacent dorsal areas with larger, widely spaced granules, remaining dorsal regions with small, dense granules, dorsolaterally and laterally granules larger, farther apart. Abd. II‒IV granulation similar to that of Abd. I but without median rows of granules. Posterior region of all segments except pronotum and Abd. VI with several sinuous transverse rows of granules similar in shape, size and density to those in medial regions (Fig. 9A). Granules on Abd. VI triangular, minute, not dense (Fig. 9D).

Labial palpus ( Fig. 8 D) with papillae A‒E, papilla spines pointed, similar; guard setae a1 and b1 minute, conical; b2, b4, d3, e1 and e2 long and slender; papilla H and guard setae h1 and h2 present, normal; other guard setae, if present, not seen; six proximal setae, four basolateral setae, four basomedian setae. Maxillary palpus without sublobal hairs, seta and spine of papilla of equal length ( Fig. 8 E). Head of maxilla with lamellae 1 and 2 extending past capitulum teeth; lamella 1 with large basal lobe. Mandible with four blunt apical teeth. Two prelabral setae, labrum with 5-4-2 setae, all setae similar in length and thickness. Postantennal organ oval, with 19‒26 oval vesicles perpendicular to the main axis; occasionally one or two small intercalary vesicles ( Fig. 8 F).

Ant. I with 7 setae, Ant. II with 11 setae. Sense organ of Ant. III with two converging sense clubs and two minute, clavate sensory rods partially covered by two cuticular lobes; three proximal guard setae ( Fig. 8 G). Ventral sense club with slightly offset basal stalk. All Ant. III setae pointed. Ant. IV ( Fig. 8 G) with six blunt, arcuate sensilla and a very thick, almost straight dorsal sensillum; microsensillum prostrate in groove; subapical organite clavate, slightly bifid at tip, rising from prominent cup-like depression; apical bulb slightly swollen. Most longer dorsal and lateral setae of Ant. IV slender but sensilliform with blunt tips, most shorter setae pointed. Ventrally, Ant. IV with one curved and two thick, straight sensilla; longer setae sensilliform; weak ventral sensory field of about 10 short, straight, blunt setae ( Fig. 8 H).

All leg setae pointed. Femur with 9 setae. Tibiotarsal setal number 12 or 13, with A and B setal whorls 7-6, 7- 5 or 6-6, respectively, regardless of leg location ( Fig. 8 I). Unguis stout, without teeth or tunica-like expansion; unguiculus a small knob.

Dorsally, cephalic seta p5 a macroseta, other setae shorter and of similar length ( Fig. 8 A). Seta v2 present, v1 absent. Six setae between posterior cephalic pseudocelli. Medial seta present anterior to a0. Pronotum with 8 setae. Mesonotum and metanotum each with m-row consisting of m1, m4 and m5; setae a4 and p5 longer than other notal setae; p3 long on metanotum; p1 slightly shorter than p2; microsensillum in shallow pit. Abdominal segments I‒III without m-setae, a2, p3 and/or p5 longer than other setae. Abd. IV with m-row consisting of m4 and m5; p2 displaced anteriorly, shorter than p1; p3 and p5 long. On Abd. V setae a2 and p1 absent, p2 displaced anteriorly; a4, p2 and p5 macrosetae; p3 a curved, tapering sensilliform seta (Figs 9C, D). Abd. VI with two unpaired medial setae.

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 chaetotaxy typically with some asymmetry. Sternum of Abd. II with 4 a-setae, medial m-seta m0 and m2, and 6 p-setae. Sternum of Abd. III similar but m-row consisting of m1 and m2. Anterior row of Abd. IV sternum with medial a0; m-row consisting of m1, m3, m4, m5; seta p1 well anterior to p2 ( Fig. 8 C). Genital aperture with five surrounding setae and two microsetae on the anterior lip. Anal lobes of Abd. VI with full complement of 19 setae on each side; seta p3 only slightly longer than p3a. Pleural regions of Abd. II and III each with an anterior sensilliform seta, that of Abd, IV with a posterior sensilliform seta.

Etymology. The specific name is derived from the Latin modifier mini-, referring to the small size of the species, and clavata , species name of the much larger Ameritulla clavata , the only previously described tullbergiid species with the same pseudocellar formula 11/010/01011.

Remarks. Psammophorura miniclavata n. sp. is placed in its genus on the basis of small size, subcylindrical antennal sensilla, PAO shape and arrangement of tightly packed, oval vesicles, presence of five pointed papillae on the labial palp and lack of crescentic ridges on Abd. VI. This last character separates Psammophorura Thibaud & Weiner, 1994 from Mesaphorura Börner, 1901 (sensu Dunger & Schlitt 2011). In the key of Dunger & Schlitt (2011) it traces to Psammophorura Thibaud & Weiner, 1994 if one assumes unknown intrageneric variation. It resembles the two previously known species of Psammophorura ( P. gedanicus Thibaud & Weiner, 1994 and P. neocaledonica Thibaud & Weiner, 1997 ) in the appearance of the PAO but lacks pseudocelli on Th. III (present in other Psammophurura spp.), lacks a tunica-like structure on the unguis and lacks the transverse groove on Abd. IV briefly mentioned in the other Psammophorura spp. In P. miniclavata n. sp. all of the pseudocelli are stellate or occasionally doubly striate (Types I, II), whereas in the other two species stellate pseudocelli occur only on the head and Abd. V; the remainder are crescentic (Type III). However, specimens of P. neocaledonica from Norway ( Fjellberg 1998) and most of those from China ( Bu et al. 2013) possessed only stellate setae, as in P. miniclavata n. sp. The new species has seven thickened sensilla on the dorsal surface of Ant. IV, whereas the previously described species each have five. Psammophorura miniclavata n. sp. also bears a strong superficial resemblance to species of Pongeiella Rusek, 1991 , but has five papillae on the labial palp, whereas Pongeiella has only two papillae ( Fjellberg 1998, 1999).

Interestingly, all three species of Psammophorura have been reported almost solely from riparian or littoral zones: P. gedanicus along the Gulf of Gdańsk , Poland, and littoral zones of Norway ; P. neocaledonica at various points on New Caledonia, also sand beaches and forest on Hainan Island, China; and P. miniclavata n. sp. from a sandy riverbank in the southern Appalachian region of North America.

Figures

FIGURE 8. Psammophorura miniclavata n. sp. A) Head, dorsal view. B) Thorax and abdomen, dorsal view. C) Abdominal segments II ‒ VI, ventral view. D). Labial palp. E) Outer lobe of maxilla. F) Postantennal organs. G) Third and fourth antennal segments, dorsal view. H) Third and fourth antennal segments, ventral view. I) Middle leg. Scales: A, 25 µm; B, C, 100 µm; D ‒ H, 10 µm; I, 20 µm.