Cherax pulverulentus, Patoka & Akmal & Bláha & Kouba, 2025

Cherax pulverulentus sp. nov.

( Figs. 1–3 View FIGURE 1 View FIGURE 2 View FIGURE 3 , 6 View FIGURE 6 )

Cherax cf. pulcher View in CoL .— Bláha et al. 2022: 5, tab. 1, fig. 2.

Cherax lorentzi View in CoL . — Patoka et al. 2014: tab. 2.

Type material. All from tributary streams to the Ayamaru Lake, Framu Subdistrict, Ayamaru District, Maybrat Regency, Southwest Papua Province, Bird's Head Peninsula, Indonesian New Guinea; collected by an anonymous Indonesian supplier. All specimens are adults.

Holotype: MZB Cru5782 , ♂ . Allotype: MZB Cru5783 , ♀ . Paratypes: MZB Cru5784 , two ♂ (paratypes 2 and 4), two ♀ (paratypes 1 and 3) .

Diagnosis. Carapace surface smooth except for 1–4 small spiniform tubercles posteriorly behind cervical groove on lateral sides of carapace. Eyes large, globular, and darkly pigmented, cornea slightly broader than eyestalk. Rostrum slender, 2.0–2.3 (x̅ = 2.2, SD = 0.1) times as long as wide, with slightly excavated margins; rostral margins carinate and with 3 prominent teeth. Postorbital ridges prominent with acute tubercle at anterior terminus. Median carina absent. Scaphocerite triangular, regularly narrowing towards apex, with single distinct spine at terminus. Antennular peduncle slightly reaching behind acumen. Antennal peduncle reaching slightly behind apex of scaphocerite. Areola 1.9–2.4 (x̅ = 2.0, SD = 0.3) times as long as wide at narrowest part. Laterally just behind cervical groove with 3 or 4 prominent anteriorly oriented spines present. Carapace 2.2–2.5 (x̅ = 2.3, SD = 0.1) times long as wide, and 1.1–1.5 (x̅ = 1.4, SD = 0.1) times longer than chela. Chela 1.9–2.3 (x̅ = 2.1, SD = 0.1) times as long as broad, and 3.9–5.0 (x̅ = 4.3, SD = 0.4) times height. Chelae of adult males with whitish uncalcified patch on lateral margin, extending from middle of palm, slightly behind base of fixed finger (propodus). Dactylar cutting edge with row of small granules and one large tubercle. Fingers with hooked tips.

Description of holotype male. ( Figs. 1–2 View FIGURE 1 View FIGURE 2 ). Adult. Body and eyes pigmented. Body subcylindrical, slightly compressed laterally. Cephalothorax 1.1 times broader than pleon; surface smooth, densely pitted, with set of 3 anteriorly oriented small spiniform tubercles laterally just posteriorly to 3 cervical groove at level of antennae and below (both sides; Fig. 2a View FIGURE 2 ). Areola 1.9 times as long as broad at the narrowest part ( Fig. 2d View FIGURE 2 ). Length of areola 31% of CL; surface smooth, pitted. Cervical groove distinct, non-setose.

Rostrum ( Fig. 2a, d View FIGURE 2 ) prominent, relatively slender, lanceolate in shape, 2.3 times as long as wide. Acumen with directly oriented spine at terminus. Median carina absent. Rostral margins elevated, anteriorly convergent throughout length to acumen, posteriorly continuing in rostral carinae on carapace. Lateral margins with 3 slightly upturned prominent teeth in distal half. Upper surface smooth, pitted, without setae, short sparse setae on outer rostral margins and on ventral side of rostrum. Rostral carinae prominent, extending as slight elevation posteriorly on carapace, gradually fading and indistinct behind middle of cephalothorax. Postorbital ridges ( Fig. 2a, d View FIGURE 2 ) prominent, strongly elevated and gradually fading. Anterior terminus of postorbital ridges with slightly upturned spiniform tubercle. Eyes ( Fig. 2a, d View FIGURE 2 ) relatively large; cornea globular, darkly pigmented, about as long as eyestalk and slightly broader.

Antennules and antennae normal in shape; antennae with cut-off terminal parts, longer than TL in living individuals. Antennular peduncle slightly reaching behind acumen, antennal peduncle reaching slightly behind apex of scaphocerite. Coxicerite of antennal peduncle with spiniform tubercle anteriorly; basicerite with 1 lateral and 1 ventral spiniform and hooked tubercle. Scaphocerite ( Fig. 2g View FIGURE 2 ) horizontal, triangular, with lamina 2.8 times as long as wide, broadest at midlength; reaching slightly behind end of antennular peduncle and acumen; regularly narrowing into apex; thickened outer lateral margin with prominent spiniform tubercle at apex reaching distinctly beyond lamina; inner margin strongly covered by dense setae.

Mouthparts typical. Epistome ( Fig. 2f View FIGURE 2 ) broadly triangular, anteriorly with rounded lobe (projection) constricted at base and with setose margins; each lateral margin covered with 2 groups of small tubercles separated by smooth place; central part smooth with distinct fovea, not pitted; epistomial zygoma prominent and thick, moderately arched with oblique arms.

Male chelipeds ( Fig. 2b, c View FIGURE 2 ) subequal in form and size. Chelae 2.2 times as long as wide and 4.3 times as long as height, strongly compressed; chela surface smooth; palm 1.5 times longer than fingers; carapace 1.3 times longer than chela; with gap between each finger when closed and with hooked tips; dactyl broad at base, regularly tapering towards tip, ventral and dorsal surface of dactyl with scattered punctuation; fixed finger hooked, merging gradually into palm of chela; fixed finger 1.6 times broader than dactyl at base. Outer lateral margin of chelae with swollen soft and uncalcified patch extending from middle of palm slightly behind base of fixed finger; surface of uncalcified patch slightly pitted; entire inner lateral margin of palm covered with slender row of more than 10 bluntly topped teeth. Dactylar cutting edge with small granular teeth, and with large prominent tooth approximately in middle of cutting edge; sparsely setose on ventral surface near base. Dactylar tip with acute, hooked spine pointing outwards at angle of approximately 45°. Propodal cutting edge with numerous small granular teeth scattered throughout entire length of fixed finger; single large tooth present in middle length of cutting edge; wide fovea in basal half of fixed finger on ventral surface; fovea setose. Propodal tip with hooked spine. Propodal and dactylar tips crossing when fingers clasp. Carpus smooth, pitted; with well-developed acute and hooked spiniform tubercle in middle of dorsolateral inner margin (mentioned tubercle is characteristic for genus Cherax ); terminating with almost directly oriented spiniform tubercle; inner lateral carpal surface covered with tiny setae; ventral surface with fovea; margins slightly elevated; inner margin with set of 6 small granules and acute spiniform tubercle oriented almost directly; outer margin with spiniform tubercle oriented directly. Merus laterally strongly depressed in basal part; surface smooth, pitted; single directly oriented spiniform tubercle present on dorsal surface; 2 directly oriented spiniform tubercles on ventral surface; ridge of small granules on entire inner ventrolateral margin, terminating with single almost directly oriented spiniform tubercle; chela about 1.8 times longer than merus. Ischium laterally strongly depressed, surface smooth and pitted, with 1 prominent and set of small spiniform tubercles on ventral margin.

Second pereiopod reaching behind apex of scaphocerite when extended. Palm as long as fingers, both sparsely setose; tips of fingers hooked. Carpus 1.7 times longer than palm. Merus 1.5 times longer than carpus and 1.5 times longer than ischium.

Third pereiopod 1.2 times longer than second pereiopod. Palm 1.8 times longer than fingers. Fingers and palm sparsely setose; tips of fingers slightly hooked. Carpus 1.4 times longer than palm. Merus 1.4 times longer than carpus and 2.3 times longer than ischium.

Fourth pereiopod reaching to about middle of scaphocerite. Propodus and dactyl setose. Dactyl slightly hooked. Propodus 1.3 times longer than carpus. Merus 1.4 times longer than carpus and 1.8 times longer than ischium.

Fifth pereiopod not reaching base of scaphocerite. Propodus and dactyl setose. Dactyl slightly hooked. Propodus 1.8 times longer than carpus. Merus 1.5 times longer than carpus and 2.4 times longer than ischium.

Dorsal surface of pleon smooth medially; pleura smooth, densely pitted; pleomeres strongly setose on ventral posterior margin.

Telson with 2 posteriorly directed spiniform tubercles caudolaterally; surface with tiny setae. Posterior half of tail fan membranous.

Uropodal protopod with single posteriorly directed spiniform tubercle on distal margin. Endopod with 2 posteriorly directed spiniform tubercles in middle and on outer margin of mesial lobe. Exopod with transverse row of posteriorly directed diminutive spiniform tubercles. The surface of the telson with tiny setose hairs.

Description of allotype female. ( Fig. 3a View FIGURE 3 ). Adult. Differing from holotype follows: Soft uncalcified patch on cheliped palm absent ( Fig. 2h View FIGURE 2 ); chelae 2.3 times as long as broad and 4.5 times as long as height; palm of chela 1.1 times longer than fingers; large tubercles on propodal cutting edges smaller, indistinct and less prominent than in holotype. Carapace 1.5 times longer than chela; cervical groove with set of 3 anteriorly directed prominent tubercles on both sides of cephalothorax. Pleon almost as broad as cephalothorax.

Thoracic sternal keel ( Fig. 2e View FIGURE 2 ): Sternite X–XII with wide and sloped median keel anterior margin to base of coxa of pereiopod 1 to base of coxa of pereiopod 3. Sternite XII with rounded narrow and small lateral processes. Small median keel at coxopodite of pereiopod 4. Sternite XIII with parallel and wide lateral processes, angle of lateral margin with large scoops.

Remarks. Cherax pulverulentus sp. nov., is genetically and morphologically most similar to Cherax pulcher , which is endemic to the Teminabuan Region, Southwest Papua Province, Indonesia (Lukhaup 2015). Both species may be easily distinguished using sequence divergence, and differ in the following characters: in body and chela coloration; the length of the second pereiopod, which reaches behind the apex of scaphocerite in C. pulverulentus , while reaching the middle of scaphocerite in C. pulcher ; and chela is 1.9–2.3 times as long as broad and 3.9–5.0 times as its height in C. pulverulentus versus 2.4 times as long as broad and 5.1 times as its height in C. pulcher . Both species can be found in two color forms, purple and blue (see below), which is the main shared feature that makes them similar.

Selected morphological characteristics of all type specimens are given in Table 2 View TABLE 2 . The holotype has cut-off second and third pereiopod on the left side within the analysis (these legs are preserved with the specimen in the same jar).

Size. Holotype male, CL = 49 mm. Allotype female, CL = 41 mm. Paratype 1

female, CL = 41 mm. Paratype 2 male, CL = 39 mm. Paratype 3 female, CL = 42 mm. Paratype 4 male, CL = 37 mm.

Coloration in life. Two color forms exist sympatrically: purple and blue.

Purple form ( Fig. 3b View FIGURE 3 ): Background color of body dark purple, marbled on carapace sides with numerous tiny pale spots. Cephalothorax dorsolaterally near cervical groove with rounded light purple spot on each side. Pleon with prominent light purple spot on both lateral sides on each pleomere, ventrolaterally pale. Chelipeds deep blue with whitish joints, palm of propodus deep blue, outer lateral margin white, soft uncalcified patch in adult males also white. Fingers deep blue with black distal third and orange tips. Row of blunt spines on inner lateral margin of palm same color as palm. Ventral surface of palm and chela same color as dorsal side. Remaining pereiopods deep blue. Uropods blue with white joints. Soft distal part of the caudal fan not pigmented. Antennal and antennular peduncle blue, flagella light purple. Maxillipeds light blue. Ventral surface of cephalothorax and pleon pale, pleopods pale in basal half and light blue in distal half. Dorsal surface of sixth pleomere with more or less prominent reddish crossshaped spot.

Blue form ( Figs. 1 View FIGURE 1 , 3a View FIGURE 3 , 6 View FIGURE 6 ): Background color bluish, brownish, dark brown or grey. Purple coloration lacking. Other coloration patterns similar to purple form.

Etymology. The meaning of the Latin term pulverulentus is “covered with dust” in reference to the many tiny dot-like spots on the carapace of the new species.

Common name. The “dusty crayfish” is proposed as a common name.

Distribution. Based on information from the supplier, the new species occurs westward in surrounding tributary streams to the Ayamaru Lake, Framu Subdistrict, Ayamaru District, Maybrat Regency, Southwest Papua Province, Bird's Head Peninsula, Indonesia ( Fig. 4 View FIGURE 4 ). The locality is on the Ayamaru limestone plateau about 250 m a.s.l. Future detailed surveys of the locality are recommended to improve the knowledge of the new species distribution.

Phylogenetics. The phylogenetic relationship inferred from two mitochondrial gene fragments (COI and 16S) results in a phylogram with a clearly defined species, C. pulverulentus sp. nov. ( Fig. 5 View FIGURE 5 ). The new species forms a strongly supported clade sister to C. pulcher with model corrected differences of 3.8 and 2.1% for COI and 16S genes, respectively. These two species form a clade as sister group to C. wagenknechtae , from which C. pulverulentus sp. nov. differing by 6.8 and 3.8% for COI and 16S genes, respectively. From three newly analysed specimens, two haplotypes were identified for both genes analysed (GenBank accession numbers PP751626 and PP751627 for COI, PP751802 and PP751803 for 16S). Both the moderate level of sequence divergence and the morphological differences described above warrant recognition of C. pulverulentus sp. nov. as distinct from the closely related C. pulcher . Phylogenetic analyses showed that previously studied individuals from Hungarian thermal waters ( Weiperth et al. 2019; Bláha et al. 2022) belong to C. pulverulentus sp. nov. (OL806576, OL806577, OL790139 for COI and OL828274, OL828272, OL780440 for 16S). These previously analysed individuals represent three other haplotypes different from the type sequences of newly described species ( Table 1 View TABLE 1 ). Additionally, two mitochondrial sequences labelled as C. boesemani (NC026227, KM501042) contain gene fragments sharing the same haplotype with our PP751626 (COI) and PP752802 (16S) haplotypes. This underlines the historical problem with proper identification of the species of Cherax originating from New Guinea, which is very difficult without comparison with other related species using basic molecular methods such as DNA barcoding.