Arlea judithnajtae, Bernard, 2017

Bernard, Ernest C., 2017, Arlea judithnajtae n. sp. (Collembola: Isotomidae), a temperate North American member of a Gondwanan genus, Zoosystema 39 (1), pp. 87-93 : 88-91

Arlea judithnajtae n. sp.

( Figs 1-3 )

TYPE MATERIAL. — United States. North Carolina, Swain County, Great Smoky Mountains National Park, Ravensford , All-Taxa Biodiversity Inventory , upland mixed Eastern hemlock-hardwoods forest, Tullgren funnel extracts, all samples within 200 m of 35°30’53.51”N, 83°17’49.00”W, elev. 600-640 m. Near pitfall 31, holotype ♀ and 2 paratype ♀ on slides, 7 paratypes in ethanol, 19.XII.2001, E. Bernard & A. Mayor, colls, deposited in the Florida State Collection of Arthropods. Thirty-seven additional paratypes, same locality: near pitfall 37, 2 ♀, 2 ♂, 3 juveniles on slides, 10 specimens in ethanol, 22.VIII.2001, P. L. Jennings & T. Goodrich, colls ; near pitfall 31, 2 specimens in ethanol, 22.VIII.2001, P. L. Jennings & T. Goodrich, colls., and 1♀ on slide, 8 in ethanol, 28.XII.2001, E. Bernard & A. Mayor, colls.; near pitfall 33, one specimen in ethanol, 22.VIII.2001, P. L. Jennings & T. Goodrich, colls., and 8 specimens in ethanol, 28.XII.2001, E. Bernard & A. Mayor, colls. Additional paratypes and specimens deposited the INHS, the GRSM Museum, the University of Tennessee Entomology Collection, and the MNHN .

ETYMOLOGY. — This species is named in memory of Dr Judith Najt, who brought a new level of descriptive precision and beautiful illustrations to the study of South American Collembola.

DESCRIPTION

Body, head

Body without pigment, posterior end rounded ( Fig. 1A ). Eyes absent. Female length 450-526 Μm (n = 6), male length 409, 453 Μm (n = 2). Ratio of Ant. I: II: III: IV as 1: 1.6: 2.0: 3.6. Cuticular surface minutely granulate, without thickenings or reticulations. Four slender prelabral setae; labrum with rounded apex, with 5-5-4 setal arrangement, middle three setae of proximal row and middle seta of middle row slender with typical sockets, other setae spine-like and arising from raised conoid bases ( Fig. 2G ). Outer lobe of maxillary palpus with strong terminal hair nearly twice the length of basal seta, accompanied by dorsolateral process equal in length to basal seta; ventral process present, longer than dorsal process; two sublobal hairs of approximately equal length ( Fig. 2D ). Labial palpus ( Fig. 2E ) with papillae A and B blunt, papillae C-E pointed; guard setae a1, b1-4, d1-4 and e1-6 present, tapering, pointed; guards a1 and b1 slender, b1 about twice the length of a1; b2 and b3 arising from a proximal prominence; lateral process (lp) large, rounded apically; 3 proximal setae, 5 basolateral setae, 4 basomedial setae. Hypostomal papilla H blunt. Postantennal organ large, broadly ovate, with 6 guard setae ( Fig. 2C ).

Antennae

Antennal segment IV on dorsal side with 7 plump sensilla, approximately 6 f-setae, papilliform subapical organite near slender, curved subapical microsensillum ( Fig. 2H ); ventrally with about 8 f-setae and short, straight subapical sensillum ( Fig. 2I ). Sense organ of Ant. III with two weakly bent sense clubs embedded in shallow groove, flanked by one dorsal sensillum and two slightly more lateral and proximal sensilla; minute spine-like sensillum present in midregion ( Fig. 2H, J ). Ant. II with one sensillum on inner side; Ant. I dorsally with spine-like microseta, ventrally with sense organ comprised of basal spine-like microseta and more anterior sensillum, spine-like seta and two or more typical setae ( Fig. 2H, K ); Legs

Longest setae of epicoxae and subcoxae sometimes weakly uniserrate ( Fig. 3A ), other leg setae smooth, acuminate, unmodified. Setal numbers of fore, middle and hind legs as follows: subcoxa I, 1-1-3; subcoxa II, 1-5-6; coxa, 4-11-10; trochanter, 9-9-9; femur, 15-15-18; tibiotarsus, 22-22-25 ( Fig. 3A ). Inner distal femoral setae shorter than outer setae. Unguis tapering, smooth, without teeth; unguiculus less than half length of unguis. Tenent hair pointed.

Abdominal appendages

Ventral tube with 4 +4 valve setae and 2+ 2 posterior setae on corpus ( Fig. 3B ). Retinaculum with 1 seta on corpus and 4 +4 teeTh. Mucro: dens: manubrium ratio 1: 15: 10. Furcal subcoxal region with 10-11 setae anteriorly, 7 setae posteriorly ( Fig. 1C ). Manubrium with 13 +13 posterior setae, outermost basal setae the longest; anterior surface with 1 +1 strong apical setae ( Fig. 3C ). Dens crenulated. Anterior surface of dens with 17 setae, posterior surface with three basal setae and two short setae in midregion ( Fig. 3C ). Mucro sickle-shaped ( Fig. 3D ). Female genital region with one pair of short setae each on anterior and posterior lips; 9 longer setae in one row between aperture and base of manubrium, with sensillum immediately posterior to each outer seta ( Fig. 3E ). Male genital plate with 2 +2 setae, surrounded by 5+ 5 setae ( Fig. 3F ).

Chaetotaxy

All body setae smooth, longest on Abd. V +VI. Thoracic sterna and Abd. II sternum without setae. Head with three pairs of post-labial setae. Dorsally, head and body typically with medial setae and paired setae as follows: head with 9 pairs of medial setae and 4 unpaired medial setae ( Fig. 2A ); Th. II with 7 pairs of setae and one medial seta; Th. III with 5 pairs and one unpaired seta; Abd. I-III each with 3 pairs; Abd. IV with one pair and 3 unpaired setae; Abd. V +VI with 2 anterior pairs of setae and three unpaired setae (a0, m0, p0); formula 9+9(4)/7+7(1),5+5(1)/3+3,3+3,3+3,1+1(3),2+ 2(3). On Abd. II, 2 or 3 most medial anterior pairs of setae (a1, a2 or a1-a3) arranged in arch below level of next most medial pair (a3 or a4) ( Fig. 2A ); Abd. III with a1-a2 pairs arranged similarly. Body sensilla similar to typical body setae except slightly shorter and thinner ( Fig. 1B ); sensilla formula for Th. II-Abd. V 4,2/2,1,1,1,5 ( Fig. 1C ). Dorsal sensilla of Th. II-III and Abd. I-III in middle setal row, that of Abd. IV in posterior row ( Figs 1B, C ; 2A ). Each side of mesonotum with one sensillum dorsally, antero-lateral corner with three sensilla, microsensillum absent ( Fig. 2F ); metanotum with dorsal and antero-lateral sensilla, microsensillum absent; one sensillum dorsally on Abd. I-III, Abd. I also with lateral sensillum; Abd. IV with one dorsal sensillum. Dorsal sensilla of Th. II-III and Abd. I-III in middle setal row, those of Abd. IV in posterior row ( Figs 1B, C ; 2A ). Abd. V+ VI dorsally with anterior sensillum and row of 3 posterior sensilla, outer sensillum of row approaching thickness of typical setae ( Fig. 2B ); one sensillum near genital plate ( Fig. 3E ).

REMARKS

Among the seven previously described Arlea spp. , A. judithnajtae n. sp. is most similar to A. psammophila. Both species have one pair of anterior manubrial setae, fewer than 20 posterior dental setae, and sensilla on Abd. V +VI are not greatly enlarged. The two species differ in the number of posterior manubrial setae (26 in A. judithnajtae n. sp., 18 in A. psammophila). They also appear to differ in setal density. The new species has eight pairs of medial setae and four unpaired medial setae on the head, whereas A. psammophila has seven pairs and three unpaired setae ( Mendonça et al. 2006). Arlea judithnajtae n. sp. is distinctive in the arrangement of anterior setae on Abd. II and III. On Abd. II the a1-2 or a1- 3 setae are arranged in an arch posterior to the line a3-a3 or a4-a4. On Abd. III the four a1- a2 setae are arranged similarly and posterior to the line a3-a3. Of the five previously described species whose chaetotaxy has been illustrated (A. adetolai, A. arenicola, A. psammophila, A. spinisetis, A. tridens), only A. arenicola has a similar feature, with the a1 setae behind the a2 line on Abd. II.

Figures

FIG. 1. — Arlea judithnajtae n. sp.: A, entire specimens; B, Abd. II and III, dorsal view; C, distribution of sensilla; posterior-row setae and furcal subcoxal setae indicated by black circles. Abbreviations: a1 and a4, first and fourth setae of anterior row; fsca, anterior furcal subcoxa; fscp, posterior furcal subcoxa; s, sensillum. Scale bars: A, 250 μm; B, 20 μm; C, 100 μm.

FIG. 2. — Arlea judithnajtae n. sp.: A, dorsal habitus and chaetotaxy;B, Abd.V+VI,right side, showing sensilla and sockets of typical setae;C, postantennal organ; D, maxillary palpus; E, labial palpus and hypostomal lobe, some guard setae not labeled; F, mesonotal sensory field, arrows indicate dorsal (D) and lateral (L) directions; G, labrum; H, antenna,dorsal view; I, Ant. IV, ventral view; J, Ant. III, subdorsal view; K, Ant. I, ventral view.Abbreviations:d, dorsal process; v, ventral process; fs, filiform seta; or, organite; s, sensillum; sm, subapical microsensillum. Scale bars: A, 100 μm; B, 20 μm; C-K, 10 μm.

FIG. 3. — Arlea judithnajtae n. sp.: A, hind leg, external view and enlargements of longest epicoxal and subcoxal setae; B, ventral tube; C, furcula, posterior view (left), anterior view (right); D, mucro; E, female genital region; F, male genital plate. Scale bars: A-C, 20 μm; D-F, 10 μm.