Thalassaphorura hainanica, Sun & Gao & Potapov, 2013

Sun, Xin, Gao, Yan & Potapov, Mikhail B., 2013, Review of Chinese littoral Thalassaphorura (Collembola: Onychiuridae), with the description of two new species, Journal of Natural History 48 (9 - 10), pp. 575-589 : 580-583

Thalassaphorura hainanica sp. nov.

( Figures 3 and 4 )

Type material

Holotype: female, Qizi Bay , 19°21 ′ N, 108°40 ′ E, sand beach (No. 31), vicinity of Changhua town , Changjiang County, Hainan Province (western coast), South China, 6April 2011, leg. Y. Bu, C.W. Huang, M.B. Potapov and N.A. Kuznetsova. Paratypes: 6 females and 5 males, same as holotype. Holotype and 5 paratypes (3 females and 2 males) are deposited in SIPPE, 2 paratypes (1 female and 1 male) in MSPU, and 4 paratypes (2 females and 2 males) in NEIGAE .

Description

Body white in alcohol. Size 750–800 µm in females, 550–700 µm in males; holotype: 800 µm. Body subcylindrical, body sides almost parallel.

Pseudocellar formula: 32/233/33343 dorsally, and 11/000/01120 ventrally ( Figures 3C–E and 4A ), subcoxa 1 of legs I–III each with 2 pso respectively. Parapseudocelli absent. Pseudopore formula: 00/011/11110 dorsally, 00/111/000x0 ventrally.

S-chaetae cylindrical, well differentiated, formula: 11/011/222121 dorsally, 11/000/ 000100 ventrally. Sp present on dorsal side of head. Tiny and blunt ms, present on Th. II–III.

Head. Antennae short and distinctly segmented, as long as head. Length ratio of Ant. I: II: III: IV as about 1: 1.5: 1.5: 2. Ant. IV with subapical organite with apex globular; basolateral ms at about two-fifths length from base. Ant. III sensory organ composed of five papillae, five guard chaetae, two small sensory rods and two smooth subequal clubs, and a lateral ms ( Figures 3B and 4B ). Ant. II with 13 chaetae. Ant. I with eight chaetae. Antennal base with distinct granulation. PAO composed 16–17 simple vesicles. Dorsal cephalic chaeta d0 present. 3 + 3 p-chaetae present between two inner posterior pso, p1 anterior to others ( Figure 3C ). Mandible with strong molar plate and four apical teeth. Maxilla bearing three teeth and six lamellae. Maxillary outer lobe with a simple palp, one basal chaeta and two sublobal hairs. Labral chaetae formula 4/142. Labium with six proximal, four basomedian (E, F, G, f) and six basolateral (a, b, c, d, e, e’) chaetae; labial type AC, papillae A–E respectively with 1, 4, 0, 3 and 2 guard chaetae ( Figure 3A ). Postlabial chaetae 4 + 4 along ventral groove ( Figure 4A ).

Body chaetotaxy ( Figure 3C–E ). Ordinary chaetae differentiated in mesochaetae and macrochaetae, ratio sp: m1: p1 on Abd. V tergum = 1: 0.5: 1.8. Th. I tergum with 5 + 5 chaetae. Th. II–III and Abd. I–III terga with 3 + 3 chaetae respectively on both side of axial line, without axial chaeta. Abd. IV tergum with one axial chaeta (m0), Abd. V tergum with one axial chaeta (a0), Abd. VI tergum with one axial chaeta (a0) ( Figure 3D ). Th. I, II and III sterna with 0 + 0, 1 + 1, 1 + 1 chaetae, respectively.

Appendages. Subcoxa 1 of legs I–III with 4, 4 and 4 chaetae, subcoxa 2 with 1, 4 and 4 chaetae respectively. Tibiotarsi of legs I, II and III with 18 (1, 8, 9) chaetae each. Unguis without teeth. Unguiculus 0.7 times as long as inner edge of unguis, with very narrow inner basal lamella ( Figure 4D, E ). Ventral tube with 1 + 1 anterior chaetae, 6 + 6 distal chaetae, 2 + 2 basal chaetae. Furca reduced to a field of fine granulation and with four small dental chaetae arranged in two rows below; only one manubrial row of chaetae present ( Figure 4F ).

Genital plate with 11–12 chaetae in females, 20–22 chaetae in males. Male organ absent. Anal valves with numerous acuminate chaetae; each lateral valve with a0 and 2a1; upper valves with chaetae a0, 2b1, 2b2, c0, 2c1, 2c2 ( Figure 4C ). Anal spines set on indistinct papillae, 0.3 times as long as inner edge of hind unguis.

Ecology

The species was collected from the sand covered by scattered vegetation on the outer section of a dune on an oceanic beach.

Etymology

To date the species has only been recorded from Hainan Island.

Remarks

The new species shows the most common pseudocellar formula (32/233/33343) known among the species of the genus ( Sun et al. 2010). It mostly resembles T. pomorskii Sun et al., 2010 described from forest litter of the Guangxi Province. They share the same pso and s-chaetae dorsal formulae, 5 + 5 dorsal chaetae on Th. I, presence of axial chaeta a0 on Abd. VI tergum, 1 + 1/6 + 6/2 + 2 chaetae on ventral tube, and small anal spines. T. hainanica sp. nov. differs from T. pomorskii by 2 + 2 pso on Abd. IV sternum (versus 1 + 1), chaetae missing on Th. I sternum (versus present), four chaetae on subcoxa 1 of leg I (versus two), and small axial chaeta a0 on Abd. V (versus much longer and sometimes asymmetrical). The most notable characters of T. hainanica sp. nov. are short anal spines and very long chaeta a0 on Abd. VI.

Figures

Figure 3. Thalassaphorura hainanica sp. nov. (A) Labial palp; (B) organ of Ant. III; (C) dorsal chaetotaxy of head and Th. I–II; (D) dorsal chaetotaxy of Th. III–Abd. VI; (E) ventral side of Abd. II–VI. Scale bars: 100 µm (C–E), 10 µm (A, B).

Figure 4. Thalassaphorura hainanica sp. nov. (A) Ventral side of head; (B) antenna; (C) anal valves; (D) leg III; (E) tibiotarsus III; (F) furcal area. Scale bars: 100 µm (A, B, D), 10 µm (C, E).