Isotomiella denticulata, Mendonça & Queiroz, 2017

Mendonça, Maria Cleide De & Queiroz, Gabriel Costa, 2017, Two new Isotomidae species (Collembola: Entomobryomorpha) from Rio de Janeiro State, Brazil, Zootaxa 4350 (2), pp. 385-395 : 386-388

Isotomiella denticulata sp.nov.

Figs: 1–16

Type material. HOlOtype female On slide 2874g CM/ MNRJ, NOva FriburgO municipality, DistritO de Mury , RiO de JaneirO , 13/IX/2015, QueirOz, C.G. cOl. LOcality: litter and sOil Of slOpes in Atlantic FOrest, NOva FriburgO municipality, 22°20’36.03”S 42°28’11.51”W, abOut 1344 meters a.s.l. Paratypes: 38 specimens (females) On slides 2874b CM/ MNRJ, 2874d CM/ MNRJ, 2874e CM/ MNRJ, 2874f CM/ MNRJ, 2874h CM/ MNRJ , 2874i CM/ MNRJ, 2874j CM/ MNRJ, 2874h CM/ MNRJ, 2874l CM/ MNRJ, 2874m CM/ MNRJ, 2874n CM/ MNRJ, QueirOz , C.G. cOl., lOcality the same as in hOlOtype .

Description. BOdy size 0.81–1.0 mm. Habitus typical Of the genus. Pigment, cuticular craters and pseudOpOres absent. Integument channels nOt visible.

Head with all chaetae Ordinary and subequal, anteriOr lOnger (155 µm) ( Fig. 1 ). Antennae lOnger (208 µm) than the head (165 µm). Ant. IV with stick-like subapical Organite prOtected by a curved chaeta, 6 subcylindrical and OvOid S-chaetae, (S1-S6), 6 supplementary S-chaetae, 4 dOrsOexternal and 2 thicker dOrsOinternal; Ant. III with abOut 35 chaetae, 2 sensOry rOds (4 µm), 2 guard sensilla (7 µm), and 1 shOrt (4 µm) external sensillum ( Fig. 2 ). Ant. II with abOut 40 Ordinary chaetae, 1 lateral-external ciliated chaeta, 2 basal micrOchaetae: 1 ventral and 1 dOrsal ( Fig. 3 ). Ant. I with 14 Ordinary chaetae and 3 ciliated chaetae (2 dOrsO-internal, 1 ventrO-external), 2 unequal sensilla (11 µm and 5 µm, respectively) and 2 basal micrOchaetae (1dOrsal, 1ventral) ( Fig. 4 ). Labrum with 4 pre-labral and 5,5,4 labral chaetae: pOsteriOr rOw with 5 Ordinary chaetae, median rOw with 2 lateral thickened and curved and 3 median Ordinary chaetae, anteriOr rOw with 2 lateral chaetae strOngly thickened (13 µm) and 2 median Ordinary chaetae ( Fig. 5 ). Maxillary Outer lObe with bifurcated palp and 4 sublObal hairs, 2 Of them situated On small integumentary papillum ( Fig. 6–9 ). Labium with a full set Of 5 labial papilla, 1 lateral prOcess and 16 guard chaetae; papilla A and B with terminal sensillum thickened at the apex, papilla C, D and E with terminal sensillum pOinted; lateral prOcess reaching half the size Of the papillum E; hypOstOmal chaetae H shOrt and thickened and hypOstOmal chaetae h1 and h2 lOnger and pOinted at the apex; mentum with 3 prOximal and 5 basOlateral chaetae; submentum with 4 basOmedian chaetae; ( Fig. 10 ). Head ventrally with axial 4+4 chaetae.

Tergites. Th. II with 11+11–10+10 axial chaetae, 3+3 lateral sensilla (8 µm, 5 µm, 8 µm) and 1+1 (Ml) lateral ciliated macrOchaetae (55 µm). Th. III with 7+7 axial chaetae, 2+2 lateral sensilla (7 µm) and 1+1 ciliated lateral macrOchaetae Ml (60 µm) ( Fig. 11 ). Abd. I with 3+3 axial chaetae, 1+1 ciliated macrOchaetae Ml (60 µm), 1+1 (Mdl) slightly ciliated mesOchaetae (30 µm) and 1+1 sligthly ciliated mesOchaetae Md (45 µm). Abd II with 3+3 axial chaetae, 1+1 ciliated macrOchaetae Ml (70 µm), 1+1 ciliated macrOchaetae Mdl (50 µm) and 1+1 ciliated macrOchaetae Md (60 µm); ventrO-lateral withOut area devOid Of chaetae. Abd III with 3+3 axial chaetae, 1+1 sensilla (8 µm), 1+1 ciliated macrOchaetae Ml (65 µm), 1+1 ciliated macrOchaetae Mdl (75 µm) and 1+1 ciliated macrOchaetae Md (65 µm). Abd IV with 3+3 ciliated axial chaetae, 2+2 ciliated macrOchaetae Ml (1+1 anteriOr and 1+1 pOsteriOr) (70 µm), 1+1 ciliated macrOchaetae Md (75 µm), 3+3 sensilla (15 µm) and few ciliated chaetae ( Fig. 11 ). Abd. V-VI with 6+6 ciliated macrOchaetae (76-86 µm), several unequally lOng ciliated mesOchaetae (39–44 µm), few Ordinary chaetae, 1+1slightly curved dOrsO-lateral sensilla spl (20 µm), 3+3 dOrsO-lateral sensilla sa, spe, spi (20 µm), 1+1 ventrO-lateral sensilla sv (15 µm), and unpaired chaetae: Ordinary mesOchaeta ao (20 µm), ciliated macrOchaeta mo (60 µm) and ciliated mesOchaeta po (35 µm) ( Fig.12 ). S-chaetae Of the minOr-type: 3,2/ 0,0,1,3,5.

Appendages. SubcOxae I–III with 1, 3 and 3 ciliated macrOchaetae; cOxae I–III with 2, 3 and 2 ciliated macrOchaetae; trOchanters I–III with 10-11, 11-12 and 11-12 chaetae, femOra I–III with 24, 24-26 and 30 chaetae Of which 3 ciliated chaetae in the external part and 1 smOOth femOral tenent hair in the internal part. Tita I–III with 27, 17 and 43–45 chaetae; distal whOrl Of leg III with 7 chaetae and 1 pOinted tenent hair ( Fig. 13 ). Unguis nOrmal (25 µm) with 1 tOOth in the distal part Of the inner margin, unguiculus lanceOlate (7 µm; Fig.14 ). Ventral tube with 4+4 apical, 3+3 anteriOr and 2+2 pOsteriOr chaetae. Retinaculum with 4+4 teeth and 1 chaeta. AnteriOr furcal subcOxae with 18 chaetae, Of which 1 ciliated, pOsteriOr furcal subcOxae with 9 chaetae, Of which 6 ciliated. Manubrium (70 µm) with 4+4 lateral, 5+5 ventrOdistal and 16+16 pOsteriOr chaetae. Dens lOng (135 µm) crenulated, with 36–43 anteriOr and 6 pOsteriOr chaetae. MucrO small (6–7 µm) tridentate, basal teeth asymmetrical ( Fig. 1–10 and 11–16 ).

Etymology. The species is named after the Latin wOrd “denticulatus”, which refers tO the presence Of a tOOth On the inner margin Of the unguis.

Remarks. The species Isotomiella denticulata sp. nov. belOngs tO the minor grOup sensu KOváč & PalaciOs- Vargas (2008) with 4 sublObal chaetae, sensillar pattern On tergites (3,2/0,0,1,3,5), number Of ventral chaetae Of manubrium (5+5) and tridentate mucrO. The new species alsO shares the anteriOr rOw, with 2 lateral chaetae strOngly thickened (13 µm) and 2 median Ordinary chaetae, On labrum with the species I. delamarei (IvOry COst), I. spinifer , I. quadriseta , I. canina , I. macedoi ( Brazil) , I. brevidens (Sumatra) , I. leksawasdii , I. edaphica ( Thailand) . But these species are dissimilar tO I. denticulata sp. nov. in several Other significant features. AmOng all species Of the genus, I. denticulata sp.nov. is mOst similar tO I. cribata (Sumatra) , since bOth shOw the same sensillary pattern by half tergite On Th. II–Abd. V-VI, nO ventrO-lateral area devOid Of chaetae On Abd. II, same numbers and arrangement Of chaetae On ventral tube, anteriOr chaetae On manubrium, pOsteriOr chaetae On dens and unpaired chaetae On Abd. V-VI. HOwever, I. denticulata sp. nov. differs frOm I. cribata in relatiOn tO the fOllOwing: Thickened anterO-lateral chaetae On labrum, inner tOOth On unguis, craters absent, 4+4 lateral chaetae On manubrium and an unusually small integumentary papillum On maxillary Outer lObe. In additiOn, the labial palp, fOr the first time described and illustrated in Isotomiella , shOws the terminal sensillum thickened at the apex On labial papilla A and B, whereas it is pOinted On labial papilla C, D and E. The same is Observed in hypOstOmal chaeta H that displays shOrt and thickened sensillum at apex. ThOugh the labial palp is cOnsidered the mOst cOmplete and least differentiated palp ( Fjellberg, 1999) in IsOtOmidae , and therefOre, a relevant diagnOstic feature fOr taxOnOmy, there is nOthing in the literature cOncerning the labial papilla in Isotomiella that allOws tO cOmpare the new species with Others Of the genus. In spite Of this, Isotomiella denticulata sp.nov. differs incOntestably frOm Other cOngeners by the presence Of an inner tOOth On the unguis, Observed fOr the first time in Isotomiella . Other differentiating features between I. denticulata sp. nov. and I. cribata , the clOsest species, are include in Table 1.

...continued on the next page Features I. cribata I. denticulata sp. nov. Ant. I chaeta 17 (3–5 ciliated) 17 (2 internal and 1 external ciliated) Labrum antero-lateral chaetae no spine like spine like

Sublobal hairs 4 4 (2 on small integumentary papilla) Labial papilla? complete

Terminal sensillum on labial papilla? thickened on papilla A and B Anterior subcoxa furcal 15–16 (5–7 ciliated) 18 (1 ciliated) Posterior subcoxa furcal 8 ciliated 9 (6 ciliated) Unguis inner margin without tooth with tooth

Tita I, II, III chaetae? 17, 27, 43-45 Manubrium lateral chaetae 3+3 4+4

Dens anterior chaetae 37–41 36–43

Mucro teeth tridentate tridentate

(basal teeth?) (basal teeth asymmetrical) Distribution Indonesia Brazil

Taxonomy

Collembola Lubock, 1870

Entomobryomorpha Börner, 1913

Isotomidae Börner, 1913

Figures

FIGURES 1 – 10. Isotomiella denticulata sp. nov.: (1) dorsal chaetotaxy of head; (2) antennal segments III – IV, dorsal view; (3) antennal segments I – II, dorsal view; (4) antennal segment I, ventral view; (5) labral chaetae; (6 – 9) sublobal hairs of maxillary outer lobe, views from different angles; (10) labial papilla A – E

FIGURES 11 – 16. Isotomiella denticulata sp. nov.: (11) dorsal chaetotaxy from Th. II to Abd. V – VI; (12) sensillar and chaetotaxy pattern of abd V – VI; (13) leg III; (14) foot complex of leg III; (15) furca, ventral view; (16) mucro, lateral view.