Yarrhpelopia, Cranston. Extensive, 2017

Cranston, Peter S., Krosch, Matt & Baker, Andrew M., 2021, Molecular evidence for deeper diversity in Australian Tanypodinae (Chironomidae): Yarrhpelopia and related new taxa, Zootaxa 4949 (1), pp. 1-23 : 11-12

‘ Yarrhpelopia ’ species ‘V20’

( Fig. 2C, K–M )

[ Pentaneurini ‘V20’. Leung, Pinder & Edward, 2011]

Material examined. AUSTRALIA: L(P), Western Australia, Jarrahdale, Wungong catchment, Seldom Seen Brook , 32°15’07”S 116°05’47”’E, 25.x.2016 (Carey) MV B8 R3.1 .

Description. Pupa (n=1 pharate, inadequately visible). Thoracic horn ( Fig. 2C ) 230 long, tubular, dilate distally, 25 wide at narrowest (base), 57 at widest (apex); plastron plate near circular, diameter 40–42; corona tapered oval, 87 long, 42 wide, ~40% length of horn. Respiratory atrium occupying ~90% of horn, weakly bilobed at connection to plastron plate at ~80% length, with internal structuring that may be struts and / or vacuoles.

Abdomen. Lateral apophyses dark yellow; armament of sparse isolated spinules. Anal lobe with, at most, very fine marginal spinules.

Larva (n=1). Head ( Fig. 2L ) length 650; cephalic ratio (l:w) 55%, subrectangular, pale yellow with occipital margin no darker. Cephalic setation ( Fig. 2H ) dorsally as in Yarrhpelopia with S7, S8, and DP near aligned at ~60° to A–P axis, and S5 slightly anterior to alignment; ventrally with S9, S10 and SSm aligned at near 45° to A–P axis, and VP lateral to S10.

Antenna ( Fig. 2L, M ) ~60% head length, 3× mandible length, segment lengths: 260: 75: 7: 6; A.R.: 2.95, ring organ at ~55–60%; basal segment ~12× as long as basal width, blade indeterminable. Style very short, 2; Lauterborn organ elongate subovoid 10, extending to mid-segment 4 ( Fig. 2M ).

Mandible ( Fig. 2K ) strongly curved, 112 long, with bluntly tapering apical tooth, short, slightly projecting inner tooth, and a very strong, tooth-like, extended mola from which seta subdentalis arises.

Ligula ( Fig. 2N ) with 5 teeth in concave row, apices of middle teeth directed slightly laterally; ligula gently broadened from midpoint; narrow area of muscle attachment occupying basal 8–10%. Paraligula bifid, with outer branch 50% length of ligula, inner shorter. Pecten hypopharyngis ( Fig. 2O ) with 9–10 straight teeth increasing in length to most anterior tooth.

Maxillary palp length 80, basal segment 35 long; ring organ at c 55% from base; crown with well-developed setae and sensilla including long 2–segmented b-seta with unequal sections.

Submentum ( Fig. 2H ) anteriorly with faint ‘creases’ of lighter sclerotisation. Dorsomentum, M appendage and vesicles not distinguishable. Pseudoradula 18 wide, essentially parallel-sided, densely micro-granulose slightly aligned linearly, posteriorly without contact to ventral hypopharyngeal apodemes.

Abdomen. Body without fringe of swim setae. Anterior parapod claws simple, pale. Anal tubules short (60). Procercus yellow, unicoloured, ~3.5× as long as wide (95 × 28), with 8 anal setae of length 410–420. Subbasal seta of posterior parapod simple, ~200 long. Posterior parapods yellow. contracted, seemingly all simple.

Remarks. Leung et al. (2011) differentiated this taxon from ‘sp. A’ (= Yarrhpelopia norrisi Cranston ) as ‘V20’ and recognised this as unique to Western Australia (WA). Although it had been reported by Bunn et al. (1986), it was not included in Cranston (1996). The sole sequence was obtained from a mature larva with pharate pupa within / amongst a batch of larvae from south-western Western Australia. Molecular placement as sister to all sampled eastern Y. norrisi ( Fig. 1 ) is credible and thus in ‘V20’ we have a morphologically distinct larva / pupa as sister to ‘core’ Yarrhpelopia . However, lacking adult material, formal description as a new species is premature and we retain Edward’s and Leung et al ‘s code for description of the larva and partial pupa. Thus, we lack a successful DNA extraction from any ‘core’ Yarrhpelopia in Western Australia that was recognised by Leung et al. (2011) as resembling Y. norrisi .

This species is a Western Australian endemic, likely limited to the moist south-west of the state, in creeks in jarrah forest (D.H. Edward pers. comm. to Cranston 1990).

Figures

FIG. 2. Yarrhpelopia Cranston, Pupa, Larva. A–C, Thoracic horns; D, E, Anal lobes (left side only); F–H, Submenta; I–K, Mandibles; L, ventral head; M, antennal apex; N, Ligula, paraligula; O, Pecten hypopharyngis. A, E, F, Y. norrisi, type locality; B, I, Y. norrisi var ‘’ST1’; D, G, Y. norrisi var. “genus D”; C, K–O, Y. ‘V20’. Abbreviations: S5–S10 cephalic setae, DP – dorsal pit, VP – ventral pit.

FIG. 1. Phylogenetic tree from Bayesian inference for Yarrhpelopia Cranston and associated taxa (Table 1) based on concatenated gene fragments. Posterior probabilities (PP) and Bootstrap support (BS from Maximum Likelihood analysis) are indicated above branches only for nodes with PP> 0.95 or BS> 70. Maximal supported nodes are indicated with an asterisk. Likelihood bootstrap support (BS), located to the right of a PP value, are cited only if>~70%, considered as supporting that node.A dash (–) for either PP or BS indicates a value below the threshold for support; unlabeled nodes are unsupported under either criterion.