Folsomia nanjingensis, Ding & Ji & Chen, 2006

Ding, Yufeng, Ji, Ming & Chen, Jianxiu, 2006, The Chinese Folsomia with a description of a new species (Collembola: Isotomidae), Zootaxa 1185, pp. 53-59 : 55-59

Folsomia nanjingensis , sp. nov.

( Figs. 1–13 )

Type material

HOLOTYPE: female, China: Jiangsu Province: Nanjing , 11­III­90, collection number 8028, coll. Kenneth Christiansen. PARATYPES: 3 females, 5 males and 1 juvenile, same data as holotype. Deposited in the Department of Biology, Nanjing University .

Diagnosis

The new species is easily distinguished from all the known species of the genus by the body sensilla as 3, 3/2, 2, 2, 3, 5, ommatidia 1+1, manubrium anterior setae as 2+2, ventral tube with 3+3 laterodistal setae, and other characters.

Description

Body length. Up to 1.5 mm.

Color. Ground colour grey, eye patches violet.

Head. Ommatidia 1+1. PAO narrow with distinct constriction, almost as long as width of base of Ant. I, and with inner denticles. 5–6 guard setae present behind PAO ( Fig. 1 ). Maxillary palp bifurcated, maxillary outer lobe with 4 sublobal hairs. Labral setal formula 4/5, 5, 4. Labium with 4+4 basomedian setae. Ventral side of head with 4+4 setae along linea ventralis (ventral groove) ( Fig. 2 ). Ant. I, II, III respectively with 2, 3, 1 basal microsensilla, and 2, 1, 5 sensilla ( Fig. 3 ).

Body chaetotaxy. Macroseta (Mac) obviously longer than ordinary seta. Sensillum (s) thinner­walled, shorter and more slender than common setae. Microsensillum (ms) thickwalled and shorter than common seta and sensillum. Formula of body macrosetae as 1, 1/ 3, 3, 3, 4 per half tergum, longest on last 3 abdominal segments 3.7–4.6 times length of mucro. Sensillar and microsensillar formula respectively as 3, 3/2, 2, 2, 3, 5 (s) and 1, 0/1, 0, 0, 0 (ms). Medial accessory p­row sensillum (accp) situated between Mac 1 and Mac 2, in front of p­row on Abd. I–III and in p­row on Abd. IV. Corner sensillum just in front of p­row on each segment of Th. II–Abd. IV. Outermost anterolateral sensilla on Th. II absent. Abd. V with 5+5 sensilla in normal positions. ( Fig. 4 ) Axial setae (common setae along median line on each side) of Th. II–Abd. III: 9–10, 6(7), 4, 4, 4. Th. III with 28–32 setae in p­row. Thorax without ventral setae.

Appendages. Tibiotarsus with many additional setae besides three rings, each with seven cheate (A1–A7, B1–B7, C1–C7). Tenent hairs absent. Unguis and unguiculus toothless. Upper and lower subcoxa with 3 (2) and 8 (6) (leg II), 4–6 and 8 (7) (leg III) setae ( Figs. 5 & 6 ), respectively. Ventral tube with 3+3 latero­distal and 5–6 posterior setae ( Fig. 8 ). Retinaculum with 4+4 teeth on rami and 1 (2 found in one specimen) large setae on ventral side of corpus ( Fig. 9 ). Anterior part of furcal subcoxa with 5 (6–7) +5 (6–7), posterior part with 4+4 setae ( Fig. 10 ). Manubrium anteriorly with 2+2 setae, apical ones large and basal ones small; posteriorly with 4+4 latero­basal, 3+3 central, 2+2 distal, 1+1 apical. Dens crenulated, anteriorly with 7, posteriorly with 2 basal and 1 medial setae ( Figs. 11 & 12 ). Mucro with 2 teeth. Ratio of manubrium: dens: mucro as 3.9–4.9: 3.6–4.4: 1.

Male genital plate. With 13 outer and 2+2 inner setae. 4 anterior and 3+3 posterior setae present in peripheral area ( Fig. 13 ).

Etymology Name of the new species is derived from the type locality.

Remarks

The new species could be easily distinguished from all the known species of the genus by the body sensilla being 3, 3/2, 2, 2, 3, 5 and setae on anterior side of manubrium being 2+2. In accordance with Potapov (2001), the new species should be placed in quadrioculata ­group, with 17 species that all share the following characters: thoracic macrochaetotaxy as 1, 1 (except as 1, 2 in taimyrica Martynova, 1973, regularis Hammer, 1953 and agrelli Gisin, 1944); microsensilla as 1, 0/1, 0, 0; corner sensillum present on each thoracic segment; medial sensillum on Abd I–III situated between Mac 1 and Mac 2; ommatidia as 0+0–2+2 and 2 ventral sensilla on Ant. I. The new species can be easily separated from other species in the quadrioculata ­group by its particular body sensilla, setae on anterior face of manubrium and other characters shown in table 1 , excluding the 3 species mentioned above with thoracic macrosetae as 1, 2.

Figures

FIGURES 1–6. Folsomia nanjingensis sp. nov. 1. PAO and omma. 2. Groups of proximal, basomedial and postlabial setae. 3. Ant. I–III (only sensilla and basal microsensilla shown). 4. Body sensillar pattern and macrochaetotaxy (sensilla, microsensilla, macrosetae and p­row of setae shown). 5. Subcoxa of leg II. 6. Subcoxa of leg III.

FIGURES 7–13. Folsomia nanjingensis sp. nov. 7. Seta­like structures (from left to right: microsensillum, corner sensillum, common seta, macroseta of Th. II). 8. Ventral tube, lateral view. 9. Retinaculum, ventral view. 10. Anterior and posterior furcal subcoxa. 11. Furca, anterior view. 12. Furca, posterior view. 13. Male genital plate and peripheral setae.

Tables

TABLE 1. Comparison of Folsomia nanjingensis sp. nov. with other members in quadrioculata­ group.

species	omma	ventral tube latero­distal setae	body sensilla	manubrium anterior setae
nanjingensis sp. nov.	1+1	3+3	3,3/2,2,2,3,5	2+2
albens	0+0	3+3	4,3/2,2,2,3,5	1+1
amplissima	2+2	4+4	4,3/2,2,2,3,5	1+1
atropolaris	1+1	3+3	4,3/2,2,2,3,5	3+3 to 6+5, mostly 4+4 or 3+4
baicalica	0+0	3+3	4,3/2,2,2,3,5	11­14, mostly 12 (1+1,
				2+2, 1+1, 1+1, 1+1)
binoculata	1+1	4+4	4,3/2,2,2,3,5	3+3 or 4+4
borealis	1+1	4+4	4,3/2,2,2,3,5	1+1
continentalis	1+1	4+4	4,3/2,2,2,3,5	1+1
manolachei	2+2	3+3	4,3/2,2,2,3,5	1+1
ozeana	1+1	3+3	4,3/2,2,2,3,5	3­5+3­5
palaearctica	1+1	3+3	4,3/2,2,2,3,5	1+1
quadrioculata	2+2	3+3	4,3/2,2,2,3,5	1+1
riozoyoshii	1+1	3+3	4,3/2,2,2,3,5	1+1
rossica	1+1	3+3	4,3/2,2,2,3,5	1+1
villosa	0+0	4+4	4,3/2,2,2,3,5	12 (1+1, 2+2, 2+2, 1+1)
vtorovi	0+0	4+4	4,3/2,2,2,3,5	1+1