Lepidocyrtus olena Christiansen & Bellinger, 1992

Bernard, Ernest C., Soto-Adames, Felipe N. & Wynne, J. Judson, 2015, Collembola of Rapa Nui (Easter Island) with descriptions of five endemic cave-restricted species, Zootaxa 3949 (2), pp. 239-267 : 254-257

Lepidocyrtus olena Christiansen & Bellinger, 1992

Figs. 7 E, 10‒11; Table 2

Material examined. CHILE, Rapa Nui, Maunga Hiva Hiva region, Cave Q15-074, baited pitfall trap 2A, 3.VII.2009, J. Wynne, 1 female on slide and 1 female in alcohol; 3 females, same locality data but in fern-moss garden, 1 on slide and 2 in ethanol.

Description. Size to 1.3 mm. Background color creamy white, with purple pigment limited to eye patch and antennae ( Fig. 7 E). Scales distributed on head, body and ventral face of furcula.

Apical bulb of Ant. IV absent; subapical sense organ not seen. Sense organ of Ant. III with 2 normal thinwalled rods. Eye patch with eyes G and H subequal and smaller than others. Eye patch valley setae not seen. Dorsal head macrosetae ( Fig. 10 A) limited to A0, Pa5, and 8‒9 in series An. Anterior head microsetae fusiform and ciliate, posterior microsetae acuminate and smooth. Prelabral and all labral setae smooth. Distal margin of labrum smooth. Outer maxillary lobe with basal and distal setae smooth and subequal; sublobal plate with 4 setae. Lateral appendage of labial papilla E slender, bent anteriorly and reaching tip of papilla. Proximal labial setae smooth. Labial triangle ( Fig. 10 B, C) setae as M1M2rEL1L2A1-5: M2 larger than M1, which is larger than r. Distribution of postlabial setae as in Fig. 10 B: setae on anterior row smooth, setae on posterior rows ciliate; 2 lateral microsetae reduced and smooth.

Body with dorsal macrosetal formula 00/0223+1+7. Mesothoracic hood produced anteriorly, blunt ( Fig. 7 E); posterior row with 6 setae ( Fig. 10 D). Chaetotaxy of metathorax complete (cf. Szeptycki 1979). First abdominal segment with a6 and 10 posterior setae. Second abdominal segment ( Fig. 10 G) with macrosetae m3 and m5; supplementary setae associated with bothriotricha m2 and a5 fan-shaped; m 4i and p5p absent; a2 ciliate; a2p and all other normal setae present and smooth; a3 anterior to sensillum as. Abd. III ( Fig. 10 H) setae mi, ml, and a2 broad fans; a3 anterior and barely reaching sensillum as; sensillum as thicker than usual and about half the length of m3; setae p3, p4, p5 and d2 normal; Li, Lm, Ll, a6, im, em, and am6 broad fans; a7 smooth, detached from bothriotrichal complex. Fourth abdominal segment ( Fig. 11 ) with 4 inner (B4, B5, B6, C1) and 9 latero-anterior (D2, D3, E1, E2, E3, E4, F1, F2, F3) macrosetae, E1 and E4 smaller than others; supplementary seta s present, all supplementary setae fan-shaped, D1 longest; T3 and D1p almost in row, closer to bothriotrix T2 than to T4; macroseta F 2 in arch with D2 and E2; posterior setae 12‒13.

Trochanteral organ with at least 12 setae. Metatibiotarsi without outstanding posterior setae. Tenent hair spatulate. Unguis ( Fig. 10 F) with 4 inner teeth, basal pair slightly sequential rather than strictly paired, teeth inserted at 39%, 42%, 67% and 86% of inner edge. Unguiculus truncate on all legs, posterior edge smooth. On ventral tube, distal row of anterior face with 2 macrosetae; lateral flaps and posterior face not seen. Manubrial plate of furcula with 3 inner and 4‒5 outer setae. Dens tubercle absent. Mucro ( Fig. 10 E) with apical tooth longer than subapical; basal spine denticulate.

Remarks. Lepidocyrtus olena belongs to the L. nigrosetosus Folsom, 1927 species group, characterized by a blunt, anteriorly produced mesothoracic hood, no head macroseta between A0 and Pa5, anterior row of postlabial setae smooth, 4 inner macrosetae on Abd. IV and truncate prothoracic unguiculus. Lepidocyrtus olena can be separated from the reasonably well-described members of this species group by the presence of ciliate labial triangle setae M1 and r, presence of Abd. II seta m3e, and absence of dental tubercle. Of the the small sized (less than 2 mm long) members of the L. nigrosetosus group, L. olena is most similar, and may be a junior synonym of L. gaeyi Denis, 1924 from French Guiana or L. schmidti Handschin, 1927 from Costa Rica; the three species differ only in that L. gaeyi and L. schmidti have three inner ungual teeth. These three species are otherwise identical in all characters described. Of the large size (more than 2.5 mm long) members of the L. nigrosetosus group, the individuals from Rapa Nui are most similar to L. nigrosetosus , L. immaculatus Folsom, 1932 and L. leleupi Jacquemart, 1976 , but the characters listed above distinguish the species. Christiansen and Bellinger (1992) suggested that L. olena might refer to morphologically distinct juveniles of L. immaculatus and thus, not a valid species. However, one of the individuals of L. olena examined is an adult female and the differences with L. immaculatus remain; L. immaculatus has a dental appendage and L. olena does not. In species with dental appendage, the structure is present even in very young juveniles.

Table 2 summarises the diagnostic differences between all species listed above. Most species belonging to the L. nigrosetosus group are poorly described and putative diagnostic characters are uncertain. The small species described by Denis (1924) and Handschin (1927) are so poorly characterised by current standards that no detailed comparison is possible. The larger members of the group also are difficult to distinguish, and in fact L. leleupi may be a junior synonym of L. nigrosetosus , differing consistently only in colour pattern, whereas the only character separating L. immaculatus from L. nigrosetosus is the number of setae along the ventral head groove ( Table 2 ).

The presence in Rapa Nui caves of a species originally described from Hawaiʻi may seem unexpected. However, members of the L. nigrosetosus species group appear to be tropical generalists that are easily transported as a result of human economic activities. It is not even certain that L. olena is native to Hawaiʻi. As mentioned above, other members of the L. nigrosetosus group occur in Central and South America and the Caribbean region. It is possible that colonization of both Rapa Nui and Hawaiʻi by L. olena might have been mediated by ancient Polynesians transporting plants (e.g., banana, sugarcane, taro, etc.) as they colonized eastward across the south Pacific ( Wynne et al. 2014). Alternatively, colonization may have occurred more recently within shipments of ornamental or agricultural plants from the South American continent.

a Sources: Christiansen & Bellinger 1992 ( L. olena ); Mari Mutt 1986 ( L. nigrosetosus ); Jacquemart 1976 ( L. leleupi ); Denis 1924 ( L. gaeyi ); Handschin 1927 ( L. schmidti ).

Figures

FIGURE 7. Lateral views of whole specimens. A) Coecobrya kennethi Jordana & Baquero. B) Coecobrya aitorererere n. sp. C) Pseudosinella hahoteana n. sp. D) Seira manukio n. sp. E) Lepidocyrtus olena Christiansen & Bellinger. All scales 200 Μm. Images 7 A, C and D were previously published in BioScience, 64, 711 ‒ 718 (2014).

FIGURE 10. Lepidocyrtus olena. A) Dorsal chaetotaxy of head. B) Chaetotaxy of labium and postlabium. Open and filled circles are coarsely ciliate and smooth setae, respectively. C) Detail of labial triangle chaetotaxy. D) Mesothorax chaetotaxy. E) Mucro and detail of mucronal spine. F) Hind foot complex. G) Second abdominal segment chaetotaxy. H) Third abdominal segment chaetotaxy, showing alternative condition of lateral setae. Open and filled circles represent macro- and microsetae, respectively, unless otherwise indicated.

FIGURE 11. Lepidocyrtus olena. Chaetotaxy of fourth abdominal segment. Open and filled circles represent macro- and microsetae, respectively. Microsetae anterior to bothriotricha T 2 and T 4 are fan-shaped, as shown enlarged for setae s and D 1.

Tables

TABLE 2. Diagnostic table for New World and Hawaiian species of Lepidocyrtus without dorsal head macrochaetae posterior to A 0 but with smooth prelabral and anterior postlabial setae and truncate prothoracic unguiculus.

Species a	Leg scales	Labial seta m1 Labial seta r	Setae along ventral groove
olena	coxa only	ciliate ciliate	4
immaculatus	femur	smooth reduced conic	4
nigrosetosus	femur	smooth or ciliate reduced conic	5–6
leleupi	femur	ciliate reduced conic	5–6
gaeyi	?	??	?
schmidti	?	??	?
continued.