Simulacala rara Hrivniak & Bojkova, 2023

Hrivniak, Ľubos, Sartori, Michel, Sroka, Pavel & Bojkova, Jindriska, 2023, Big diversity in a small hotspot: two new species of Leptophlebiidae (Insecta, Ephemeroptera) from New Caledonia, ZooKeys 1143, pp. 71-88 : 71

publication ID	https://dx.doi.org/10.3897/zookeys.1143.96148
publication LSID	lsid:zoobank.org:pub:6550FE87-6B87-411C-8259-56068C03CC59
persistent identifier	https://treatment.plazi.org/id/5A2F303F-9F02-44C7-A511-AC1BAE447ABB
taxon LSID	lsid:zoobank.org:act:5A2F303F-9F02-44C7-A511-AC1BAE447ABB
treatment provided by	ZooKeys by Pensoft
scientific name	Simulacala rara Hrivniak & Bojkova
status	sp. nov.

Treatment

Simulacala rara Hrivniak & Bojkova sp. nov.

Material examined.

Holotype. Female larva, New Caledonia; Chagrin, Fridoline River. (Loc. 98/2022), -20.4902778, 164.2572222, 70 m a.s.l.; 03.02.2022; leg. J. Bojková, Ľ. Hrivniak. Deposited in MZL GoogleMaps . Paratypes. 2 larvae (1 larva mounted on slide and deposited in IECA, 1 larva deposited in MZL-DNA extracted from both), same data as holotype GoogleMaps .

Other material examined

(used for DNA extraction; cuticular skin preserved and deposited in MZL). 2 larvae (GBIFCH 01121825 and GBIFCH 01121826), same data as holotype .

Description of larva.

Body length of middle-instar larvae 3.0-3.5 mm. Size of late-female and male instar larvae unknown. General coloration of body yellowish with dark brown markings. Body covered by sparse hair-like setae.

Head. Prognathous, antennae more than 2 × longer than head. Coloration yellowish with dark brown markings as in Fig. 5B View Figure 5 .

Mouthparts. Shape of labrum and clypeus as in Fig. 5D View Figure 5 . Labrum ca. 2.3 × wider than long. Length and width of labrum approximately same as length and width of clypeus (Fig. 5D View Figure 5 ). Dorsal surface of labrum with scattered hair-like setae and two irregular rows of bristle-like setae along anterior margin (Fig. 5D View Figure 5 , left half; setae marked with dots). Anterior margin medially deeply cleft, with two large denticles (Fig. 5D View Figure 5 ). Ventral surface with long hair-like setae submedially and anterolaterally (Fig. 5D View Figure 5 , right half). Lingua with well-developed lateral processes and deeply cleft anterior margin. Superlinguae laterally extended with bristle-like setae along dorsal margins, lateral margins acute (Fig. 6C View Figure 6 ). Both mandibles with two incisor groups, separated from base and equipped with denticles (Fig. 5E, F View Figure 5 ). Prostheca of right and left mandible similar, indistinctly divided into two branches, each with long filaments apically. Shape and setation of maxillae as on Fig. 6D View Figure 6 . Maxillary palps three-segmented, first and second segment of approximately same length, length of third segment 0.73-0.80 × length of second segment. Third segment triangular and broad at base. Shape of glossae and paraglossae as in Fig. 5G View Figure 5 . Labial palps three-segmented, length of second segment 0.82-0.95 × length of first segment, length of third segment 0.61-0.68 × length of second segment. Third segment triangular, broad at base, with spine-like setae on inner and dorsal margins (Fig. 5G View Figure 5 ).

Thorax. Yellowish with dark brown markings dorsally (Fig. 5A-C View Figure 5 ).

Legs. Yellowish, without apparent pattern (Fig. 5B, H View Figure 5 ). Maximum width of tibiae 1.41-1.60 × width of tarsi. Tibiae oval in cross-section. Inner margins of femora indented in apical half. Claws with 3-5 large denticles (apically progressively longer); apical part of claws hooked with a row of small denticles as in Fig. 5I View Figure 5 .

Abdomen. Terga brownish with pale markings forming median stripe and pair of medio-lateral elongated maculae (Fig. 5A View Figure 5 ). Terga darkened sub-laterally. Sterna yellowish, without pattern (Fig. 5C View Figure 5 ). Postero-lateral spines on abdominal segments VI-IX (Fig. 5J, K View Figure 5 ). Spines on segment IX apically indented (Fig. 5K View Figure 5 ). Posterior portion of sternum IX triangular, rounded apically (Fig. 5J View Figure 5 ).

Gills. On abdominal segments I-VII. Shape of all gills alike; all gills divided from near base. Each branch narrow and distinctly elongated (e.g. gill IV in middle-instar larvae reaches or exceeds end of abdomen), smoothly tapered to apex (Fig. 5A, L, M View Figure 5 ). Lamellae pale grey, tracheae greyish.

Caudal filaments. Yellowish, terminal filament little longer than cerci. Cerci length approximately 1.2 × body length.

Subimago, imago, and egg.

Unknown.

Etymology.

The species is named according to its rare occurrence in Grande Terre. Feminine.

Generic attribution.

The larva of the genus Simulacala was defined by Peters et al. (1990) based on the following morphological characters: i) inner margin of third segment of labial palps has thick heavy spines; ii) glossae of labium are straight; iii) denticles on claws are progressively larger apically, except apical denticle larger to much larger; iv) third segment of the maxillary palps is 3/4 to 4/5 length of second segment; and v) abdominal gills I-VII are deeply forked and 2 portions of lamellae overlap; each portion is long and smoothly to abruptly tapered to apex. Mary (2017) added two additional characters for the identification of the genus: i) anterior margin of labrum with 2 or 3 large denticles and ii) length of the distal segment of the labial palp approximately equal to its maximum width.

Almost all generic characters mentioned above correspond to S. rara sp. nov. suggesting its position in the genus Simulacala . The only exception is the length of the distal segment of the labial palps, reaching approximately 1.5 times its width. Nevertheless, other characteristics of labial palps, notably the presence of dense spines on the inner and dorsal margins correspond to the genus Simulacala .

The genus Fasciamirus is most closely related to Simulacala and their larvae possess similar morphological characters as indicated by Peters et al. (1990). They can be distinguished based on the presence of dark bands on femora of all legs in Fasciamirus , whereas these bands are absent in Simulacala ; this applies to imagos, subimagos and larvae ( Peters et al. 1990). According to our observation, this coloration pattern is visible already in younger larval instars of Fasciamirus . Femora of S. rara sp. nov. do not exhibit dark bands, suggesting an attribution to the genus Simulacala . Additionally, longer and wider triangular shape of the third segment of maxilary palp in S. rara sp. nov. is characteristic for the genus Simulacala (see Peters et al. 1990: fig. 110 and Fig. 6D View Figure 6 ). Fasciamirus possesses a rather narrower triangular and a shorter third segment of maxilary palps (see Peters et al. 1990: fig. 104 and Fig. 6B View Figure 6 ).

According to the larval morphological characters given by Peters et al. (1990) and Mary (2017), S. rara sp. nov. is attributable to the genus Simulacala based on following characters: i) third segment of labial palps broad, triangular, with spine-like setae on inner margins (Fig. 5G View Figure 5 ); ii) gills lanceolate, narrow (width of both branches less than 1/3 of length) and divided at base (Fig. 5L, M View Figure 5 ); iii) tibiae of all legs oval in cross-section; iv) denticles on claws are progressively larger apically with apical denticle larger to much larger (Fig. 5I View Figure 5 ); v) glossae of labium are straight (Fig. 5G View Figure 5 ); vi) segment 3 of the maxillary palps is 3/4 to 4/5 length of segment 2 (Fig. 6D View Figure 6 ); vii) femora of all legs without dark apical and distal maculae (Fig. 5B View Figure 5 ).

We do not rule out the possibility that S. rara sp. nov. may represent a separate monospecific genus, as the larval morphological convergences in New Caledonia are extreme and adults, bearing more informative systematic traits, are unknown. Nevertheless, the larvae of S. rara sp. nov. are morphologically most similar to the genus Simulacala as currently defined. Therefore, we describe this species therein until the large-scale revision of New Caledonian Atalophlebiinae is completed, based on larger number of mitochondrial and nuclear markers. This revision is currently in preparation.

Larval morphological diagnostics.

Simulacala rara sp. nov. can be distinguished by the combination of the following characters: i) all gills narrow, smoothly tapering to the apex, distinctly elongated and reaching or exceeding end of abdomen in middle-instar larvae (Fig. 5A, L, M View Figure 5 ); ii) femora and mesobasisternum without dark markings (Fig. 5B, H View Figure 5 ); iii) anteromedian margin of labrum with two large denticles (Fig. 5D View Figure 5 ).

Differential diagnosis.

Three other species of the genus Simulacala occur in Grande Terre: Simulacala notialis Peters, Peters & Edmunds, 1990, S. massula Peters, Peters & Edmunds, 1990, and S. milleti Peters, Peters & Edmunds, 1990. Simulacala rara sp. nov. can be distinguished from all known species by distinctly elongated and narrow gills (Fig. 5A, L, M View Figure 5 ). Simulacala notialis is characterised by shorter (gill IV reaches tergum VII) and wider gills that taper abruptly toward the apex ( Peters et al. 1990: fig. 131). Simulacala massula and S. milleti have gills that taper gently toward the apex, but are distinctly shorter (gill IV in middle-instar larvae reaches tergum VII-IX) and that are wider ( Peters et al. 1990: figs 132, 135, respectively) than in S. rara sp. nov. with narrow gills and gill IV reaching or exceeding end of abdomen in middle-instar larvae. Simulacala massula can be distinguished by a blackish macula on the anterior margin of the mesobasisternum and apically darkened femora ( Peters et al. 1990: fig. 133) from S. rara sp. nov. and S. milleti with femora and thoracic sterna without any pattern.

Distribution and habitat preferences.

The species was found in the single stream Fridoline (a small stream, 3-5 m wide) in the northern province of Grande Terre (Fig. 1 View Figure 1 ), on ultramafic bedrock. Its catchment includes the area of old chromite mines and active nickel laterite mines. We did not find elevated concentrations of dissolved metals (Fe, Mn, Cr, Ni) in the stream water, but magnesium content was very high (66.7 mgl-1) and bed surface was rich in iron precipitates. The stream was eutrophic, with total P concentration 26.2 µgl- 1 and about 70% cover of bed substrate by filamentous green algae. The sampled section had riffles with slightly turbulent flow and gravel substrate, and predominant slow-flowing part with sandy and fine gravel substrate (Fig. 7D, E View Figure 7 ). Larvae were collected from fine gravel and sand behind stones in the riffles. They avoided similar fine-grained sediments in the slow-flowing part of the section.