Cryptopygus tingus, Gabriel C. Queiroz & Maria Cleide De Mendonça, 2010

Gabriel C. Queiroz & Maria Cleide De Mendonça, 2010, Two new Isotomidae species (Collembola) from Espírito Santo State, Brazil, Zootaxa 2480, pp. 37-44 : 37-42

Cryptopygus tingus sp. nov.

Figs 1–13 , Tab. 1

Type material. Holotype female. Brazil, Espírito Santo State, Sooretama municipality, Sooretama Biological Reserve (ICMBio), forest litter of the Atlantic Forest , about 200 m above the sea level and 40km from the coast line. Local coordinates: 19°3'8.53"S, 40°8'56.12"W, 25.iv.2008, collection number CM 1958, Gabriel C.

Queiroz coll. Paratypes: 9 (Nº 1958 CM/ MNRJ) on slides, same date as holotype. Deposited at Museu Nacional do Rio de Janeiro, Brasil.

Description. Body length of holotype 0.58 mm, paratypes 0.35–0.65 mm. Color white, no trace of pigment. Tegumentary granulation very fine, without craters.

Body chaetotaxy. Common setae smooth and acuminate. Macrosetae stiff, becoming increasingly longer towards the last abdominal tergites ( Figs 1, 2 ). Formula of macrosetae per half tergite as: 11/33347. Macrosetae of abdominal segments V–VI measuring about 50 µm, almost as long as antennal segment IV (55 µm). Axial setae per half tergites as: 75/33334, abdominal tergite V–VI with unpaired setae a0, m0 and p0 measuring 20, 40 and 15 µm, respectively ( Fig. 2 ). Sensillar formula per half tergites as: 22/12232 (s), 10/ 00000 (ms); microsensillum on thorax II almost indistinguishable from nearby sensilla. Dorsal sensilla on abdominal segment V–VI smooth and oval ( Fig. 1 ); ventral sensilla (1+1) near genital opening ( Fig. 13 ).

Antennae. Slightly longer than head diagonal, with common, acuminate setae of different sizes. Ratio antennae: head diagonal = 1.2:1. Antennal segment I with about 16 setae, 2 basal microsetae (one ventral and one dorsal) and 2 sensilla in ventroapical position ( Fig. 4 ). Antennal segment II with about 23 setae, 4 basal microsetae (one dorsal, one ventral and 1+1 lateral), and one long lateral external sensillum. Antennal segment III with about 25 setae; sensory organ consisting of 2 small freely exposed sensilla, 2 guard sensilla and one external microsensillum; no basal microseta ( Fig. 5 ). Antennal segment IV with subapical organite protected by one curved setae, 7–8 cylindrical sensilla; without apical papilla ( Figs. 5, 6 ). Ratio of antennal segments I:II:III:IV= 1:1.5:1.8:2.8.

Head. Without eyes. Postantennal organ large and oval, as long as the width of antennal segment I, surrounded by 6 guard setae ( Fig. 3 ). Mouth parts of chewing-type. Labrum with 3 prelabral and 5,5,4 labral setae. Maxillary capitulum with six fringed lamellae and two subequal teeth. Maxillary outer lobe bifurcated, with three sublobal hairs and one basal seta. Labial palp with 5 papillae and 15 setae (a1, b1–4, d1–4, e1–6), one lateral process smaller than half of papilla E. Hypostomal setae distinct, H thick blunt, smaller than others, h1 and h2 long and curved (h2 with enlarged base) ( Fig. 7 ). Head with 5+5–4+4 setae along linea ventralis.

Appendages. Unguis small, without internal tooth. Unguiculus toothless, short and lanceolate. Tibiotarsi I–III with 24, 24, 30 setae, respectively; tenent hair pointed, not differentiated from other setae; distal whorl with 7 setae on tibiotarsi I–III ( Fig. 8 ). Tibiotarsus II with B4 and B5 setae.

Ventral tube with 4+4 apical and 3+3 posterior setae, without anterior setae ( Fig. 9 ). Retinaculum with 4+4 teeth and one seta on corpus ( Fig. 10 ). Anterior furcal subcoxa with about 12 setae, posterior with 5 setae. Manubrium with 1+1 distal long seta on anterior side, 14+14 setae on posterior side and 2+2 small lateral setae. Dens long and crenulated, with 24 anterior and 6 posterior setae ( Fig. 11 ). Mucro bidentate, very small, without setae ( Fig. 12 ). Ratio manubrium:dens:mucro = 12:18:1. Male genital opening as in Fig. 13 .

Discussion. Cryptopygus tingus sp. nov. belongs to a group of species without eyes and pigment (sensu Thibaud 1996), which includes C. albaredai (Selga, 1962) , C. axayacatl Palacios-Vargas & Thibaud, 2001 , C. benhami Christiansen & Bellinger, 1980 , C. bibasiosetis Potapov & Stebaeva, 1999 , C. delamarei Poinsot, 1970 , C. caussaneli Thibaud, 1996 , C. debilis (Cassagnau, 1959) , C. exilis (Gisin, 1960) , C. scapelliferus (Gisin, 1955) and C. tribasiosetis Potapov & Stebaeva, 1999 . Among these species, C. benhami is the only that presents an internal tooth on unguis. Table 1 lists the characters that distinguish these species.

In the group of blind species Cryptopygus tingus sp. nov. is more related to C. debilis due to similarities in the shape and size of the sensillum on abdominal segment V–VI, the number of dorsal and lateral manubrial setae, the shape and size of the mucro, according to the redescription of C. debilis by Ellis (1976). Nevertheless, C. debilis has craters on abdominal segment V–VI, 2+2 anterior setae in the manubrium, a longer dens bearing 30 setae, and the macrosetae of body not so well developed. Unfortunately, the whole sensillar chaetotaxy of C. debilis is unknown. Comparing the sensillar pattern of C. tingus sp. nov. to some species of the mentioned group, which are included in Fjellberg (2007), it is possible to verify that C. scapelliferus and C. albaredai share a similar pattern with the new species by presence of the lateral sensilla (al) from thoracic segment II to abdominal segment I. However, C. scapelliferus does not have the accp sensillum on abdominal segment II and both, C. albaredai and C. scapelliferus , have a microsensillum between the 2 sensilla on the abdominal segment III and 7 sensilla in the abdominal segment V–VI. One of these sensilla on abdominal segment V–VI of C. scapelliferus and C. albaredai is ventral, located near the base of manubrium and probably near to the genital opening of adults. Palacios-Vargas & Thibaud (2001), in the description of C. axayacatl , also make reference to the presence of a ventral “microsensillum” in the abdominal segment V–VI which is close to the genital opening of an adult. The same sensillum was also observed in the new species. It is also worth noting that C. tingus sp. nov. shares some other similarities with C. scapelliferus like shape and size of mucro, number of anterior manubrial setae, number and position of setae on dens and also the fact that the macrosetae become longer towards the tip of the abdomen. According to Fjellberg’s drawing (2007: Fig. 46 F), C. scapelliferus does not have the a0 seta on sixth abdominal segment, while p0 and m0 are present. In C. tingus sp. nov. all 3 unpaired setae are present.

Etymology. From the indigenous brazilian language Tupi: tinga is a word that means “white”, in a reference to the absence of pigment of the new species.

Figures

FIGURES 1 – 13. Cryptopygus tingus sp. nov.: 1, dorsal sensilla and macrochaetae of th. II to abd. V – VI (other seta omitted); 2, chaetotaxy of abdominal segments IV and V – VI, dorsal view, with detail of abd. V – VI: smooth oval sensillum; 3, postantennal organ and its surrounding seta; 4, ant. segment I, ventral view; 5, ant. segments II, III and IV, dorsal view; 6, sensilla of ant. segment IV (common seta omitted), dorsal view; 7, left labial palp; 8, femur and tibiotarsus of leg III, lateral view; 9, ventral tube, lateral view; 10, tenaculum; 11, manubrium, anterior view, right dens anterior and left dens posterior view; 12, mucro; 13, male genital opening and its surrounding seta.