Willowsia jacobsoni ( Börner, 1913 )

Katz, Aron D., 2017, A new endemic species of Willowsia from Florida (USA) and descriptive notes on all New World Willowsia (Collembola: Entomobryidae), Zootaxa 4350 (3), pp. 549-562 : 552

Willowsia jacobsoni ( Börner, 1913)

Figs 3, 4 , 11 , 16

Material examined. USA: Puerto Rico, Aguada, Coloso Sugar Cane Mill , on sugar cane litter, 16.vi.1999, F. Soto- Adames, 2 on slides ( INHS 810,148–810,149 ) ; Puerto Rico, Aguada, Coloso Sugar Cane Mill , on sugar cane litter, 17.vi.1999, F. Soto-Adames, 4 females, 2 (1 male) on slides ( INHS 810,150–810,155 ), 15 in ethanol ( INHS 810,156 ) .

Complement to description based on American specimens. Habitus as in Figs 3 and 4 . Scales long basal rib type ( Fig. 11 ) and absent on antennae, legs, and furcula. Dorsal chaetotaxy of the head as in Figure 16 : row An with 6 mac; anterior mac A0, A2, A3, A5 present; 3+3 median mac, M1, M2, M4 present, M3 always absent; 4+4 sutural mac, S2, S3, S4, S5 present, S6 as mic; post-sutural mac Ps5 absent. Outer maxillary lobe with 3 sublobal hairs. Prelabral setae ciliate. Labral papillae each with multiple seta-like projections. Labial triangle as MrEL1L2A1–5, r always present. Lateral process of labial palp straight, blunt, reaching tip of labial papilla E. Cephalic groove with 5+5 ciliate setae. Th. II without median mac and 2+2 posterior mac. Abd. I with 1+1 mac.

Ecology. This species occurs in leaf litter, and is abundant in agroecosystems such as sugar cane fields and banana leave axils.

Distribution. Pantropical, including Hawaii and Puerto Rico.

Remarks. Willowsia jacobsoni is the only member of the genus with the following combination of characters: color pattern as in Figs 3 and 4 ; long basal rib type scales ( Fig. 11 ); scales absent on antennae, legs, and furcula; labral papillae with multiple projections; prelabral setae ciliate; labial triangle seta r present ; outer maxillary lobe with 3+3 sublobal hairs; dorsal head with 3+3 median mac, 4+4 sutural mac, mac S0 and Ps5 absent ( Fig. 16 ); Th. II with 0+0 median mac and 2+2 posterior mac; Abd. I with 1+1 mac; Abd. II with 2+2 inner mac; Abd. III with 2+2 inner and 3+3 lateral mac; and Abd. IV with 5+5 inner mac.

In scale morphology and scale distribution, this species is very similar W. buski and W. nigromaculata : they all have long basal rib type scales that are absent on the antennae, legs, and manubrium. However, W. jacobsoni can be differentiated from W. buski and W. nigromaculata by color pattern and head and body chaetotaxy: head mac Ps5 is absent in W. jacobsoni (present in W. buski and W. nigromaculata ) and W. jacobsoni has 3+3 inner mac on Abd. III ( W. buski and W. nigromaculata have 2+2). See Table 1 for additional diagnostic characters.

The material observed for this study is in general agreement with Mari Mutt’s (1981) detailed morphological description, except Th. II mac a5 is incorrectly labeled as m 4 in Mari Mutt (1981).

Figures

FIGURES 1 – 4. Habitus: 1, Willowsia buski; 2, Willowsia nigromaculata; 3, Willowsia jacobsoni (male); 4, Willowsia jacobsoni (female). Scale bars = 200 µm.

FIGURES 5 – 14. Scales: 5 – 7, Willowsia pyrrhopygia sp. nov.; 8 – 10, Willowsia mexicana; 11, Willowsia jacobsoni; 12, Willowsia buski; 13, Willowsia nigromaculata; 14, Americabrya arida. Scale bars = 1 µm.

FIGURES 15 – 19. Head dorsal chaetotaxy: 15, Willowsia buski; 16, Willowsia jacobsoni; 17, Willowsia nigromaculata; 18, Willowsia mexicana; 19, Willowsia pyrrhopygia sp. nov. Scale bars = 100 µm.