Oudemansia chenorum, Palacios-Vargas & Bu, 2020

Palacios-Vargas, José G. & Bu, Yun, 2020, New records of Collembola from marine littoral sand of Hainan Island, China with description of a new Oudemansia species (Neanuridae: Pseudachorutinae), Zootaxa 4810 (1), pp. 117-130 : 119-127

Oudemansia chenorum sp. nov.

Figs 1–23

Material examined. Type specimens: Holotype, female (slide no. 8-1) ( SHNM), China, Hainan Province, Sanya city, sandy beach of Ximaozhou island , flotation of sand samples, 18°14’N, 109°22’E, 17-III-2011, Y. Bu and C. W. Huang cols. Paratypes: 1 female (slide no. 8‒2), same data of holotype; 5 females [slides no. 1–3 ( UNAM), 6, 7, 11 ( SHNM)], 1 male (slide no. 9) ( SHNM) , China, Hainan Province, Sanya city, sandy beach of Ximaozhou island , flotation of sand samples, 18°14’N, 109°21’E, 5-IV-2011, Y. Bu, C. W. Huang, M. B. Potapov and N. A. Kuznetsova cols. Additional material: 2 juveniles (slides no. 4, 5) ( UNAM), 1 juvenile (slide no. 12) ( SNHM), same locality data as holotype .

Description. Adult body length average (n=8) 1.24 mm (range 0.99–1.51 mm). Color dark purple/black; intersegmental areas not developed on thorax, slightly on abdomen ( Fig. 1 ). Cuticle with strong granulation ( Fig. 2 ). One pair of pseudocelli on head close to seta p5 ( Figs 12, 14 ) and on abdominal segments I, III and IV close to sensorial setae ( Figs 5 , 19 ). Thorax and abdomen without paratergites.

Antennae subequal to head length (about 220 µm). Ant. I–II–III+IV ratio = 1:1.1; 1.3. Dorsal side of Ant. IV with trilobed apical bulb displaced subapically, close to subapical organite, both set in a tegumental depression; ms absent; only four well-differentiated sensilla (S3, S4, S7 and S8); S1 and S2 present but very thin and acuminate; small setae “i” and “x” present ( Fig. 7 ). Ant. III organ with Sgd smaller and thinner than sensilla, displaced towards Ant. IV; internal microsensilla long, half-length of Sgv and freely exposed, ventral microsensillum present, Sgv slightly curved ( Fig. 9 ). Ant. I and II with 7 and 11 setae respectively ( Fig. 8 ).

Head. Eyes 8 + 8 in three groups, one with eyes A, B, C and D, other with H and another with E, F and G; Oc1–3, Oc3 smaller than others ( Figs 12, 13 ). PAO absent. Five dorsal cephalic setae (d1–5), only four subdorsal setae (sd2–5); p1–3 present, p2 smaller than others; without unpaired setae, v and c rows absent ( Fig. 12 ). Labrum elongated as a beak, with strong proximal granulation ( Figs 4 , 11 ), four prelabral setae and 9 labral setae; formula: 4/3, 4, 2; similar to Pseudanurida , last two seta (a) longer and thicker than others ( Fig. 11 ). Labral sclerotification with two slight apical short projections ( Fig. 10 ).

Mandible with two strong teeth, one basal and one median, 12 small apical teeth ( Fig. 15 ); maxilla styliform ( Fig. 16 ). Hypopharynx complex with two serrate lamella and 9 apical teeth ( Figs 3 , 15 ). Labium truncate apically, with C seta long and laterally displaced, setae A–B in normal position and D apically displaced, papillated seta L absent ( Figs 3 , 17 ). Two pairs of postlabial setae.

Chaetotaxy composed of ordinary mesosetae of different size (smallest 11 µm) and long sensorial setae (62 µm), posterior setae becoming longer towards Abd. VI, ratio ordinary setae of row a: sensorial setae approximately 1: 4.3. Sensorial setae formula by half body: 022/11111 ( Figs 12 , 19 ). Th. I with 2 + 2 setae. Axial setae formula by half body: 122/22222; never with three rows of setae on any segment of body. Legs chaetotaxy I–III as follows: Subcoxa I–1,2,2; Subcoxa II–0,1,1; Coxa–3,6,7; Trochanter–6,6,6; Femur–13,12,11; Tibiotarsus–18,18,17, no tenent hairs, without M seta. Length of tita I–III 53, 54 and 58 µm respectively, ungues thick, with a strong basal inner tooth ( Fig. 18 ). Ratio ungues III: Tita=1:1.2; ratio ungues III: mucro =1.4. Abd. V with pairs of 5 dorsal setae, sensorial setae in p3. Four anal spines, two a1 (40µm) and two a2 (33 µm) ( Figs 2 , 19 ). Anal spine a1 slightly curved, a2 straight. Other setae on Abd. VI normal (not spiniform), m1 longer than m2.

Ventral chaetotaxy. Thorax without ventral setae. VT with 2 + 2 setae; Abd. II with 2 + 2 ventro-internal setae. Tenaculum strong, with 3 + 3 teeth; Abd. III with 2 + 2 ventrointernal setae and 1 + 1 ventrolateral.Abd. IV with 4 + 4 ventro-lateral; 2 + 2 ventro-external and 1 + 1 ventro-internal seta ( Fig. 20 ). Furcula complete and well developed; manubrium with 7 + 7 setae; dens short, with coarse granulation and 6 setae; mucro more than 1/3 of dens, no clear separation between them, slightly tapering with a small hooked apex; ratio mucro: dens; manubrium = 1: 2.3; 2.8 ( Fig. 21 ). Female genital plate with 3 + 3 pregenital setae, 6–9 circumgenital setae and 2 eugenital setae ( Fig. 22 ). Male genital plate with 3 + 3 pregenital setae, no circumgenital setae, but two circular organs, each with six short cylindrical structures similar to sensilla, 5 + 5 eugenital setae ( Figs 6 , 23 ). Ventral lateral anal valves with 14 + 14 setae and 3 hr microsetae ( Fig. 20 ). Posterior anal valve with 3 ventral setae.

Distribution. China (Hainan). Only known from the type locality.

Etymology. This species name is dedicated to both Professor Jian-Xiu Chen, retired professor from Nanjing University and Professor Jian Chen from Hubei University of China, for their contributions to the knowledge of Collembola taxonomy and spider’s biology, respectively, and for their friendship and help given to the authors for many years.

Remarks. Oudemansia chenorum sp. nov. has small anal spines a2 (a1> a2), so it seems related with Oudemansia subcoerulea Denis, 1948 , O. dubia Denis 1947 and O. petiti Delamare Deboutteville & Massoud, 1964 . Oudemansia petiti is similar to O. esakii Kinoshita, 1932 but differs in the number of manubrial setae (14 vs. 20). The new species has same kind of male genital organs as O. petiti but differ in the number of mandibular teeth, which are very numerous in P. petiti (20) and in two rows. In P. chenorum sp. nov. the anal spines have different length and seta a3 is normal. Oudemansia petiti lacks Oc2 and Oc1 is short (very long in the new species) and one dental seta is distally displaced from the other five.

Figures

FIGURE 19. Oudemansia chenorum sp. nov. Dorsal abdominal chaetotaxy and magnification of pseudocelli.

FIGURE 20. Oudemansia chenorum sp. nov. Ventral abdominal chaetotaxy.

FIGURES 1–6. Oudemansia chenorum sp. nov. 1, dorsal view of Abd. I–III showing intersegments; 2, cuticular granulation, anal spines and setae on Abd. VI; 3, mandible, labium and hypopharynx; 4, labrum; 5, pseudocellus on Abd. IV; 6, genital plate of male and anal valves. Scale bars: 100 µm in Fig. 1, 50 µm in Figs 2–6.

FIGURES 7–11. Oudemansia chenorum sp. nov. 7,Ant. III and IV in dorsal view, with magnification of apical bulb and subapical organite (or); 8, Ant. I–II dorsal view; 9, Ant. III and IV in ventral view; 10, labral sclerotification; 11, labrum.

FIGURES 12–14. Oudemansia chenorum sp. nov. 12, head and thorax chaetotaxy; 13, ocular area; 14, cephalic pseudocellus (arrow indicate anterior part of head).

FIGURES 15–18. Oudemansia chenorum sp. nov. 15, hypopharynx and mandible; 16, maxila; 17, labium; 18, tibiotarsus III.

FIGURES 21–23. Oudemansia chenorum sp. nov. 21, furcula; 22, female genital plate; 23, male genital plate.