Denisiella diomedesi, Palacios-Vargas, José G., 2007

Palacios-Vargas, José G., 2007, A new species of Denisiella (Collembola: Sminthurididae) from Panama and new records for D. sexpinnata (Denis, 1938), Zootaxa 1637, pp. 63-68 : 64-67

Denisiella diomedesi sp. nov.

Figs 1–13

Description. Male. Length 650 µm. Body and antennae purple. Legs and furcula almost transparent, with small purple pigment at their bases. 6 + 6 pigmented eyes.

Antennae classically bent as in all Sminthurididae males, elbowed between Ant. II and III; ratio of antennal segments about 1: 0.9; 0.4; 0.5. Ant. I with 7 setae, two of them very small and thin ( Fig. 1 ). Ant. II with 22 setae, two trichobothria (Tra1, Tra2) one microsensilla, and modified setae b1–6 on the same tubercle ( Fig. 2 ). Ant. III with 10 setae, three setulae, one trichobothrium, one ventral microsensillum and the antennal organ with a pair of oval separate microsensilla ( Fig. 3 ), seta c1 lamellate and c 3 in the shape of a big spine. Ant. IV simple, elliptical with about 50 setae, only one olfactory setae difficult to distinguish ( Fig. 4 ). The chaetotaxy of the head as in Fig. 5 , on the anterior part of the middle line are two spine-like setae and below them a peculiar structure of one big alveolus with four strong setae with fine ciliations.

Leg I coxa with one seta, trochanter with three setae, femur with 11, tibiotarsus basally on the outer edge with four small organs, bladder-like, thick-walled, and highly elevated ( Fig. 6 ), with about 30 setae, and two microsetae. Leg II coxa with one seta and one spine, trochanter with three setae, femur with 11 setae, two of them much longer ( Fig. 7 ), tibiotarsus with 29 setae, two microsetae and one stout, thicker dorsal seta and one organ with four cone-like spines ( Fig. 8 ). Leg III coxa with one seta, trochanter with three thin and small setae and one small spine, femur with 10 setae and one microseta, tibiotarsus with four stout and coarsely serrate spine-like setae, 26 setae and three microsetae, pretarsus with one setae on each side. Unguis without tunica and with one small inner tooth, unguiculus with long filament surpassing the unguis. Tibiotarsal organ absent ( Fig. 9 ).

Thoracic segmentation not evident. Dorsal chaetotaxy of small abdominal segment with thick setae ( Fig. 13 ). Ventral tube with 1 + 1 seta. Corpus of tenaculum with two setae, basal appendix and three teeth. Genital and anal segments ankylosed into a single mass. Genital plate of the male with one pregenital seta and 4 + 4 eugenital setae. Manubrium with seven pairs of setae, one of them longer ( Fig. 10 ). Dens with 42 posterior setae, two of them very long, internal ones thicker ( Fig. 10 ), anterior surface with the setal formula 3, 3, 3, 2, 2, 1, 1, 1 ( Fig. 11 ). Mucro with two lamellae, the inner serrate, with about 18 serrations, outer lamella smooth, one mucronal outer seta ( Fig. 12 ). Length of manubrium 57 µm, dens 193 µm, and mucro 84 µm, ratio of manubrium, dens and mucro as 1: 3.3: 1.5. Maximum length in µm of setae on head 40, body 37, dens 61, tibiotarsus 42.

Type locality. Panama: Panama Province, Chepo, Chichebere, in pitfall traps, rice paddyfield, B. Zachrisson coll., 15.viii.2002.

Type material. Holotype and two paratype males will be kept at Laboratorio de Ecología y Sistemática de Microartrópodos, Sciences Faculty, UNAM, México.

Etymology. This species is dedicated to Dr. Diomedes Quintero (Universidad de Panamá), for his help in the study of springtails from Panama.

Discussion. The sexual dimorphism of species in the genus Denisiella is very remarkable. Antennae of males are highly modified as a clasping organ and there are four organs on tibiotarsus I, apparently found in all the species of the genus. The modified setae on tibiotarsus II and the proximal cuticular conical spines are also present in D. maesorum but were not mentioned in the original description of the latter species.

The structures on Ant. II and III of D. diomedesi sp. nov. are similar to D. maesorum, except that Ant. II lacks the b6. The most diagnostic character of D. diomedesi sp. nov. and not found in other species the genus is the nasal organ on the head formed by a basal insertion and four ciliated setae in the same alveolus. The 4 bladder-like organs on tibiotarsus I of the new species are smaller than in other species.

Figures

FIGURES 1 – 5. Denisiella diomedesi sp. nov.: 1, right Ant. I, dorsal view; 2, left Ant. II, ventral view; 3, left Ant. III, dorsal view; 4, right Ant. IV, ventral view; 5, cephalic chaetotaxy.

FIGURES 6 – 9. Denisiella diomedesi sp. nov.: 6, tibiotarsus I; 7 femur II; 8, tibiotarsus II; 9, tibiotarsus III.

FIGURES 10 – 13. Denisiella diomedesi sp. nov.: 10, chaetotaxy of manubrium and left dens, posterior side; 11, chaetotaxy of right dens anterior side; 12, apex of right dens and mucro, posterior side; 13, chaetotaxy of small abdomen.