Rickia appendicifera Santam., Enghoff, & Reboleira, 2016

Santamaria, Sergi, Enghoff, Henrik & Reboleira, Ana Sofia P. S., 2016, Hidden biodiversity revealed by collections-based research-Laboulbeniales in millipedes: genus Rickia, Phytotaxa 243 (2), pp. 101-127 : 103-105

Rickia appendicifera Santam., Enghoff, & Reboleira , sp. nov. ( Figs 1−5 )

Mycobank MB 815401

Diagnosis:—Receptacle triseriate, a: 2, m: 2, p: 2(–3). Primary appendage conspicuous, consisting of a dark brown, straight, slightly constricted, rigid fragment, about twice as long as any of the other similar parts, i.e., secondary appendages and antheridia. Median series with m

1

twice as long as m

2

.

Type: — IRAN. Chiraz, clayey mountain north of the city, on Chiraziulus kaiseri (Mauriès 1983) ( Cambalidae ), 16 February 1937, E.W. Kaiser leg., C-F-95116, C-F!, holotype designated here; BCB-SS ·E602ab, d, BCB!, isotypes designated here.

Etymology:— appendicifera , meaning “bearing an appendage”; referring to the conspicuous primary appendage,

especially remarkable when the thalli are seen on the host cuticle under a dissecting microscope.

Thallus hyaline except for the dark brown foot, the base of appendages and the stalk cells of antheridia. Total length 78−94 μm. Receptacle triseriate. Basal cell twice as long as broad, its distal part wedged between the lower cells of the marginal series, separated by oblique septa from cells a 1 and p 1.

Anterior series consisting of two cells. Cell a 1 triangular in section, lacking appendages or initial appendiculate cells. Cell a 2 triangular to trapezoidal in section, including on its upper-inner corner the perithecial stalk-cell ( Fig. 1 , VI), bearing on the outer-upper corner one antheridium with its appendiculate cell ( Fig. 3 , an; Fig. 5 , apc, scan).

Median series consisting of two cells, rounded at both extremes, fully surrounded by the two lateral series, borne just above a 1 and p 1 and ending slightly above p 2 ( Fig. 1 ). Cell m 1 2–3 times as long as m 2.

Posterior series composed of 2(–3) cells ( Fig. 1 ). Cell p 1 without appendages, similar to a 1. Cell p 2 longer than broad, bearing (1–)2(–3) secondary appendages (very rarely one of these is replaced by a single antheridium) on its outer-upper corner and the primary appendage on its top. When more than one secondary appendage is present, they are overlapping. Cell p 3, if present, bears a secondary appendage similarly as p 2. Basal cell of primary appendage 1.5 times as long as broad, bearing the terminal long cell, the latter with a sallow base, a rather long, dark brown, and constricted middle part, which is about twice as long as analogous parts of the secondary appendages, and a hyaline,

short, often damaged terminal portion ( Fig. 2 , pa).

Antheridium 7–11 × 3–4 μm, typically isolated on cell a 2, above a subtriangular hyaline appendiculate cell, an elongate dark brown and basally constricted stalk-cell, and the terminal flask-shaped phialide ( Fig. 3 , an; Fig. 5 , apc,

scan).

Secondary appendages 17–23 μm, consisting of a hyaline distal portion contrasting with a dark brown lower part,

which is constricted near the septum of separation from the appendiculate cell ( Fig. 4 , sa).

Perithecium 42–54 × 19–24 μm, solitary, stout, ovoid, entirely hyaline (even the trichogyne scar), with a slightly differentiated short neck and a blunt apex with rounded and poorly defined lips.

Discussion:— Determining the position of the primary septum in this species is not easy, because the basal cell of the primary appendage does not show the usual dome-shaped form as in the remaining species of Rickia included in this work. We have defined the position of primary septum ( Fig. 3 , a) in agreement with what mature thalli or even sporelings show. This species appears absolutely isolated among the other species in this study. A short trichogyne was observed on an immature thallus, pointing towards the antheridium ( Fig. 5 , tr).

Position on host:— Rickia appendicifera is randomly distributed on the host; thalli were found on the head,

antennae, the dorsal part of body rings, and the legs, the highest density around the most anterior pairs of legs.

Notes on hosts:— Chiraziulus kaiserii belongs to order Spirostreptida , family Cambalidae . Chiraziulus has two known species, both endemic in Iran, and is the only cambalid genus occurring in the western Palaearctic region, being isolated from its presumed closest relative by more than 7000 km distance ( Reboleira et al. 2015).

Figures

FIGURES 1–5. Rickia appendicifera. Figs 1–2. Nearly mature thalli. Figs 3 and 5. Immature thalli. Fig. 4. Two paired mature thalli. (Figs 1, 5, SS·E602b; Figs 2, 4, C-F-95116; Fig. 3, SS·E602a.) (For interpretation of abbreviations see under materials and methods.) Scale bars for Figs 1, 3, 5 = 20 μm; for Figs 2, 4 = 25 μm.