Onychiurus antennalis, Sun & Zhang, 2012

Sun, Xin & Zhang, Feng, 2012, Two new species of Onychiurus (Collembola: Onychiuridae) from Eastern China, Journal of Natural History 46 (31 - 32), pp. 1895-1904 : 1900-1903

Onychiurus antennalis sp. nov.

( Figure 4 ; Table 1)

Type material

Holotype female, two male paratypes and seven female paratypes. China: Zhejiang Province: Lin’an: Xitianmu : Baihe. 12 April 2005, litter, berlese extraction, Jian-xiu Chen leg. (C9234). All deposited in NJU.

Description

Body length: female 1.6–1.8 mm, male 1.5 mm; holotype 1.8 mm. Body shape: cylindrical, Abd. III –IV more or less broadened. Body colour: white in alcohol .

Pseudocelli formula 32 / 122 / 33343 dorsally, 11 / 000 / 01010 ventrally, subcoxa 1 of legs I–III with one pso each. Parapseudocelli: subcoxa 1 of legs I–III without psx, 1+1 psx on Abd. I sternum, near base of ventral tube. Pseudopore formula as 00 / 011 / 11110 dorsally, 00 / 111 / 000x0 ventrally.

Formula of s-chaeta 11 / 012 / 222120 dorsally. Sp present on head ( Figure 4A ). The s-microchaetae tiny and blunt, present on Th. II and III dorsally.

Head: antennae short and distinctly segmented, as long as head. Length ratio of antennal segments I: II: III: IV = 1: 1.5: 1.5: 2. Ant. I with 10 chaetae. Ant. II with 16 chaetae. Ant. III sensory organ composed of five papillae, five guard chaetae, two small rods and two granulated sensory clubs, both morel-like; lateral ms just behind sensory organ. Ant. IV subapical organite with apex globular; basolateral ms at about one-third length from base; presence of a small, finely granulated, flat apical swelling at the apex of antenna, invaginated apical bulb absent ( Figure 4B ). Antennal base with smaller granulation. PAO composed of 52–60 compound vesicles arranged in two rows along axis of organ. Dorsal cephalic chaeta d 0 present. 4+4 p-chaetae between posterior a-pso on head, p 1 anterior to others. Mandible with strong molar plate and four apical teeth. Maxilla bearing three teeth and six lamellae. Maxillary palp simple with one basal chaeta and two sublobal hairs. Labral chaetae 4 / 342. Labial papillae of AC type, papillae A–E respectively with one, four, zero, three and four guard chaetae. Labium with six proximal, four basomedian (E, F, G and f) and six basolateral (a, b, c, d, e, e’) chaetae. Postlabial chaetae 4+4 along ventral groove.

Body chaetotaxy: ordinary chaetae differentiated into meso-chaetae and macrochaetae, ratio sp: m1: p1 on Abd. V = 1: 0.8: 1. Th. I tergum with 7–8+7–8 chaetae. Th. II–Abd. III terga respectively with 3+3 chaetae along axial line, without axial chaetae. Abd. IV tergum with two axial chaetae (m 0 and p 0), Abd. V tergum without axial chaeta, Abd. VI tergum with two axial chaetae (a 0 and m 0) ( Figure 4E ). Th. I, II and III sterna with 0+0, 1+1 and 1+1 chaetae respectively between legs. Subcoxa 1 of legs I, II and III all with four chaetae, subcoxa 2 with one, four and four chaetae respectively.

Appendages: tibiotarsi I, II and III with 22 (11, 8, 3), 21 (11, 8, 2) and 21 (11, 8, 2) chaetae. Unguis without teeth. Unguiculus slender and pointed, 0.6 times as long as inner edge of unguis, with broad inner basal lamella ( Figure 4C ). Ventral tube with 7–8+7–8 distal chaetae, without anterior and basal chaetae. Furca reduced to a finely granulated area, with four small dental chaetae in one row posterior to furcal rudiment; three manubrial rows of chaetae present ( Figure 4D ).

Genital plate with 18 circumgenital chaetae and two genital chaetae in female, 35–38 circumgenital chaetae and eight genital chaetae in male. Anal valves with numerous acuminate chaetae; each lateral valve with chaetae a 0 and 2a 1; upper valve with chaetae a 0, b 0, 2b 1, 2b 2, c 0, 2c 1, 2c 2 ( Figure 4F ). Anal spines set on distinct papillae, 0.4 times as inner edge of hind unguis.

Ecology

Under leaf litter, stones and bricks.

Etymology

Named for its peculiar antennal morphology.

Remarks

Onychiurus antennalis sp. nov. is easily diagnosed by the presence of its apical swelling on Ant. IV and 1+1 pso on Th. I tergum. It is similar to Onychiurus gulinensis sp. nov. in ventral pseudocellar formula (11 / 000 / 01010), distal whorl of tibiotarsi (11 chaetae), chaetotaxy on head (sp present, 4+4 p-chaetae between posterior a-pso on head) and chaetotaxy on ventral tube. They can be distinguished by the characters listed in Table 1.

Figures

Figure 4. Onychiurus antennalis sp. nov. (A) Dorsal side of head, showing d0, S-chaetae, PAO and pso; (B) Ant. III–IV with sensory club; (C) distal side of leg III; (D) furcal area; (E) dorsal side of Abd. IV–VI with pso, s-chaetae marked; (F) anal valves. Scale bars: 0.1 mm (A–F).