Entomobrya manuhoko Bernard, Soto-Adames & Wynne

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 : 241-246

Entomobrya manuhoko Bernard, Soto-Adames & Wynne , n. sp.

Figures 1‒3

Material examined. CHILE, Rapa Nui, Maunga Hiva Hiva region, holotype female dissected and mounted on three slides, 1 female paratype, 1 male paratype, 5 juvenile paratypes, Cave Q15-074, direct search of fern-moss gardens, 13 July 2009, J. Wynne, coll. Additional paratypes: 1 male, 1 female, and 1 juvenile, same data as holotype except collected at fig tree in entrance; 3 specimens, sex undetermined, from Cave Q15-076/078, direct search of fern-moss gardens in entrance 3, 0 4 July 2009, J. Wynne, coll.; 2 juveniles from Cave Q15-127, opportune collection within entrance, 0 2 July 2009, J. Wynne, coll.

Description. Males and females similar except where noted. Length up to 2.3 mm. macrosetae cylindrical, rounded at tip ( Fig. 3 E). In ethanol background color light cream-yellow, markings primarily reddish to brownish violet ( Figs. 1 A‒D). Ant. I pale, Ant. II pale proximally, red-violet distally, Ant. III pale at base otherwise pigmented, Ant. IV completely violet. Head ( Fig. 1 B) with strong interantennal band, trident-shaped spot between eyepatches, and lunate marking posteriorly; genae with prominent light violet patches extending nearly head length ( Fig. 1 A). Prothorax with violet spots dorsally. Mesothorax, metathorax and Abd. I with three broken bands of pigment, forming large spots. Abd. II and III with five broken longitudinal bands, including a lateral band on each side. Median band of spots on mesonotum, metanotum and Abd. I‒III tergites connected by thin line of pigment. Lateral pigment on Abd. IV consisting of anterior V-shaped marking and compact posterior spot. Dorsum of Abd. IV with large clear central area surrounded by spots and posterior transverse band joined to form a five-armed figure ( Figs. 1 B, C), medial stripe lacking; anterior spots on Abd. IV of male weakly connected. Abd. V with arched transverse band, Abd. VI with posterior band. Femora and tibiotarsi with wide purple bands. Furcula not pigmented. Juveniles with smaller, discontinuous spots on Abd. IV.

Apical bulb of antenna weakly bilobed or entire, pin seta entire; apex of Ant. IV with mix of smooth, pointed setae, multiciliate setae, and sensilliform setae of various lengths ( Fig. 2 E). Prelabral setae ciliate, labral setae smooth. Labral papillae with single points ( Fig. 2 A). Labial palp ( Fig. 2 B) with all guard setae except e4, e5 and e7; guard setae a1 and b1 stout, arising well up on papilla B; lateral process of papilla E stout, rounded apically, not reaching spine base; five proximal setae present. Labial triangle setae in female arranged as M1M2REL1L2A1‒5, seta M2 shorter than but similar to neighboring setae ( Fig. 2 C). Outer lobe of maxillary palp with three sublobal hairs ( Fig. 2 D). Eight eyes in eye patch, eyes A and B slightly larger than others ( Fig. 3 A).

All tibiotarsi with prominent false joint at midpoint, marked by transverse cuticular grooves ( Fig. 1 G), and with several enlarged ciliate setae among thinner, more coarsely ciliate setae ( Figs. 1 H, I). Inner edge of unguis with four teeth; inner basal paired teeth arising at more than half the distance from ungual base; dorsal tooth and lateral teeth present, lateral teeth not reaching paired inner teeth. Unguiculus lanceolate, with inner edge smoothly curved, outer edge finely serrated. Tenent hair spatulate; all tibiotarsal setae ciliate except for stout, smooth, slightly sinuate ventro-subapical seta on hind tibiotarsus ( Figs. 1 I, 2G). Trochanteral organ of hind leg with up to 18 straight, smooth microsetae of various lengths ( Fig. 2 F). Ventral tube anteriorly with 12+ 12 or 13+13 ciliate setae, distal three setae on each side thickened and much longer than others; 21 posterior ciliate setae, distal four setae thicker than others; each valve with 3 smooth and 10‒14 ciliate setae ( Fig. 2 H). Tenaculum with four teeth on each arm and one anterior seta on the corpus. Manubrial plaque with 8+8 ciliate mesosetae arranged slightly asymmetrically and 3+3 pseudopores arranged in a triangle; 10+10 subdistal ciliated manubrial mesosetae in one row ( Fig. 2 J). Mucro with strong anteapical tooth meeting basal spine; uncrenulated part of dens about 1.7× mucro length ( Fig. 2 K).

Cephalic seta A1 a mesoseta, A0‒A5 macrosetae; An0 and An1 mesosetae; M row with three macrosetae; S0 and S2 posterior to S1 setae, S5 and S 5i macrosetae or large mesosetae. Macrosetal arrangement on posterior region of head asymmetrical with two macrosetae in Ps row and varying numbers in other P-rows ( Fig. 3 A). H1 area with 4 setae, H2 with 1 seta (A5), H3 without setae, H4 with 2 setae, H4’ with 4 setae, H5 with 2 setae ( Fig. 3 A).

Thoracic chaetotaxy ( Fig. 3 B) asymmetrical. On mesonotum, anterior region (zone A) with up to 22 macrosetae exclusive of collar; medial (M) zone with pseudopore and 1‒4 macrosetae; lateral (L) zone, 3 macrosetae; Pm zone, up to 33 macrosetae; Pl zone, 5 or 6 macrosetae. On metanotum, M zone with pseudopore and 7‒10 macrosetae; L zone, 1‒3 macrosetae; Pm zone, 11‒12 macrosetae; Pl zone, 8 macrosetae. Mesonotum with two distinct medial lines of mesosetae ( Fig. 3 B) and 3‒4 irregular rows of mesosetae along posterior margin ( Figs. 1 D, 3B), sockets in this posterior field elevated in contrast to more anterior mesosetal sockets ( Fig. 1 D). Metanotum with similar posterior field but without distinct medial mesosetal rows.

Mesosetae dense and greatly variable in length and diameter ( Fig. 1 E). Abdominal segments II‒V each with single posterior row of short mesosetae; Abd. I with increased number of mesosetae at lateral ends of row ( Figs. 3 B‒D). Abd. I with 12+12 macrosetae and two small, lateral sensilla. On Abd. II setal field A1 with two macrosetae and a sensillum, field A2 with 6‒7 macrosetae. Abd. III without macrosetae in field A3 (macroseta A1 absent), field A4 with 2 macrosetae and smooth sensillum; field A5 with one macroseta; 3 macrosetae, sensillum d2 and a minute microseta in vicinity of bothriotrix m5. Adult Abd. IV ( Fig. 3 C) with asymmetrical arrangement of 14‒19 macrosetae in inner region: field A6 without macrosetae; A7 with 5 macrosetae; A8 with 3‒5 macrosetae; A9 with 3 or 4 macrosetae and 1 or 2 smooth microsetae; A10 with 3‒5 macrosetae. Lateral region with 14‒17 macrosetae. Abd. V with 20 asymmetrically arranged macrosetae; Abd. VI without macrosetae. Juvenile Abd. IV macrosetal numbers and arrangement also asymmetrical ( Fig. 3 D).

Male genital plate with 18 thick setae, with enlarged bases and narrowly rounded apices ( Fig. 2 I).

Etymology. The species was named by combining two Rapanui terms, manu and hoko. Manu is Rapanui for “insect” and used as a noun, while hoko is used as a modifier. Hoko is an ancient form of Rapanui dancing where the dancer, usually male, jumps up and down ( Fortin 2009).

Relationships. The body pattern of Entomobrya manuhoko n. sp. is quite similar to that of E. pulchra Schäffer, 1897 ( Schäffer 1897, Christiansen 1963) ( Argentina, Bolivia) and the Brazilian E. pseudodecora Rapoport, 1962 ( Rapoport 1962) , but differs in the shape of the dorsal pattern on Abd. IV. In E. manuhoko n. sp.

adults have a five-armed figure without a medial band ( Fig. 1 B), fancifully resembling a squat penguin or a swimming turtle. The pattern on Abd. IV of E. puchra and E. pseudodecora has disconnected spots or a weak to strong medial band of pigment, which E. manuhoko n. sp. lacks. The mesonotum of E. manuhoko n. sp. has lateral and medial spots, similar to that of E. pseudodecora , whereas E. pulchra has a U-shaped figure. The outer edge of the unguiculus of E. manuhoko n. sp. is serrated, whereas the unguiculi of the other two species are illustrated as smooth. The descriptions of E. pulchra and E. pseudodecora are brief and lack details of the chaetotaxy.

Figures

FIGURE 1. Entomobrya manuhoko n. sp. A) Lateral view. B) Dorsal view, intact specimen. C) Dorsal view, thoracic and abdominal segments after clearing and mounting. D) Head, dorsal view. E) Mesosetae of various sizes on abdominal segment V. F) Right submedial region of mesonotum showing range of setal socket sizes. G) Tibiotarsal pseudojoint. H) Variation in tibiotarsal seta thickness and ciliation. I) Tibiotarsal setae and location of smooth subapical seta. Inset: closeup of smooth seta. All scales are in Μm.

FIGURE 2. Entomobrya manuhoko n. sp. A) Anterior edge of labrum. B) Labial palpus. C) Setae along labial base. D) Maxillary palpus. E) Apex of Ant. IV. F) Trochanteral organ. G) Hind foot. H) Chaetotaxy of ventral tube: an, anterior; la, lateral; po, posterior. I) Male genital plate. J) Manubrial plate region; black circles with slash represent pseudopores, two mesosetae drawn to show relative sizes. K) Mucro.

FIGURE 3. Entomobrya manuhoko n. sp. A) Head, adult dorsal chaetotaxy. B) Adult chaetotaxy of Th. II ‒ Abd. II. C) Adult chaetotaxy of Abd. IIII ‒ VI. D) Late juvenile chaetotaxy of Abd. IV. E) Macroseta. Scales for A ‒ D = 200 Μm.