Cherax (Astaconephrops) gherardii Patoka, Bláha and Kouba, 2015

Patoka, Jiří, Bláha, Martin & Kouba, Antonín, 2015, Cherax (Astaconephrops) gherardii, a new crayfish (Decapoda: Parastacidae) from West Papua, Indonesia, Zootaxa 3964 (5), pp. 526-536 : 527-535

Cherax (Astaconephrops) gherardii Patoka, Bláha and Kouba , new species

Figs. 1–2

Diagnosis. Carapace surface smooth with exception of one to five small spiniform tubercles posterior cervical groove on lateral carapace. Eyes large, pigmented, cornea slightly broader than eyestalk. Rostrum lanceolate in shape with excavated margins. Rostral margins with three prominent teeth. Rostral carinae prominent. Postorbital ridges prominent with one acute tubercle at anterior terminus. Scaphocerite regularly narrows into apex with a single distinct spine at terminus. Antennular peduncle reaching slightly behind acumen, antennal peduncle reaching slightly behind apex of scaphocerite. Uncalcified patch on lateral margin of chelae of adult male pale, translucent, extending from about middle of palm to about one fifth of opposable propodus (fixed finger). Propodal cutting edge with row of small granules and one large tubercle. Chelipeds blue with orange joints. Palm of chelae blue in basal part, pale in distal part. Fingers orange, in distal third black with hooked orange tips. Row of blunt spines on inner lateral margin of palm light blue. Other walking legs deep blue in color. Gonopores of both sexes normal in shape and position.

Description of holotypic male. ( Figs. 1 , 2 B–G, 3A). Body and eyes pigmented. Eyes not reduced. Body subovate, slightly compressed laterally. Cephalothorax 1.2 times broader than pleon.

Rostrum ( Fig. 2 D) relatively slender, lanceolate in shape, 3.6 times as long as wide, reaching slightly beyond end of second segment of antennular peduncle. Terminus of acumen straight, not deflected or upturned. Median carina absents. Rostral margins elevated, anteriorly convergent throughout length to acumen, posteriorly forming rostral carinae. Each lateral margin bearing three slightly upturned prominent teeth on distal half. Upper surface smooth and without setae, sparsely short setose hairs present on outer rostral margins and on ventral side of rostrum. Rostral carinae prominent, extending as slight elevation posteriorly on to carapax, gradually fading and indistinct behind middle of PCL (a well-developed rostral carinae is characteristic to subgenus Astaconephrops ). Postorbital ridges ( Fig. 2 D) prominent, strongly elevated posteriorly, gradually fading, remaining 1/3 of PCL indistinct. Anterior terminus of postorbital ridges with slightly upturned spiniform tubercle. Eyes ( Fig. 2 D) relatively large; cornea globular, darkly pigmented, about as long as eyestalk and slightly broader.

Antennulae and antennae normal in shape; the antennae similarly long as TL. Antennular peduncle reaching slightly behind acumen, antennal peduncle reaching slightly behind apex of scaphocerite. Coxicerite of antennal peduncle with spiniform tubercle anteriorly; basicerite with one lateral and one ventral spiniform and hooked tubercles ( Fig. 2 B). Scaphocerite ( Fig. 2 G) horizontal, with lamina 2.7 times as long as broad, broadest at midlength; convex in distal part becoming narrower at base, but otherwise is straight; reaching slightly behind the antennular peduncle; regularly narrows into the apex; thickened outer lateral margin with prominent spiniform tubercle at apex reaching distinctly beyond the lamina; rounded inner margin strongly covered by setae.

Epistome ( Fig. 2 F) with subcordiform cephalis lobe bearing weak cephalomedian projection and constricted at base; lateral margins of lobe not thickened; each lateral margin covered with two groups of small tubercles separated by smooth area; central part smooth with fovea, not pitted; inner side of cephalomedian projection strongly setose, ventral surface smooth with sparse short hairs, not pitted; epistomal zygoma prominent and thick, moderately arched with oblique arms.

Areola 1.8 times as long as broad at narrowest part. Length of areola 28% of TCL; surface smooth and pitted. Cervical groove distinct, non-setose. Carapace surface smooth, pitted, with set of 4 anteriorly directed small spiniform tubercles laterally just posteriorly to cervical groove at level of antennae and below, only the lowest one prominent.

Male chelipeds and chelae ( Fig. 2 C, E, 3A) equal in form and size. Chelae 2.6 times as long as broad and 7.1 times as long as deep, strongly compressed; chela surface smooth, pitted; palm 1.6 times longer than fingers; carapace 1.2 times longer than chela; fingers slightly gaping; dactyl broad at base, tapering slightly towards tip; opposable propodus triangular, merging gradually into palm of chela; opposable propodus 1.8 times broader than dactyl at base. Outer lateral margin of chelae with swollen soft and uncalcified patch which extends from about middle of palm to about one fifth of opposable propodus, surface of the uncalcified patch slightly pitted ( Fig 3 ); entire inner lateral margin of palm covered with slender row of more than ten bluntly topped teeth. Dactyl cutting edge with small granular teeth mainly near base, and with one large prominent tooth near middle of cutting edge; setose in posterior part of ventral surface. Dactyl tip with acute, hooked spine pointing outwards at an angle of approx. 45°. Propodal cutting edge with numerous denticles which are more distinct near base; one large prominent tooth at middle of cutting edge; setose in posterior part of ventral surface. Propodal tip with acute, moderate hooked spine. Propodal and dactyl tips slightly crossing when fingers clasp. Carpus smooth, pitted; with one welldeveloped acute and hooked spiniform tubercle in the middle of dorsolateral inner margin (mentioned tubercle is characteristic for genus Cherax ); terminated with one spiniform tubercle oriented straight. Ventral carpal surface covered with tiny hairs and with fovea; fovea not pitted; margins slightly elevated; inner margin with set of 3 or 4 small granules and one acute spiniform tubercle oriented almost straight; outer margin with one spiniform tubercle oriented straight. Merus laterally depressed in basal part; surface smooth and pitted; single directly oriented spiniform tubercle present on dorsal surface; row of three directly oriented spiniform tubercles present on ventral surface; row of small granules on entire inner ventrolateral margin; chela 2.0 times longer than merus. Merus laterally strongly depressed; surface smooth and pitted; single spiniform tubercle present on ventral margin.

Second pereiopod reaching slightly behind apex of scaphocerite. Palm as long as fingers; fingers and palm sparsely setose; tips of fingers hooked. Carpus 2.0 times longer than palm. Merus 1.6 times longer than carpus and 2.7 times longer than ischium.

Third pereiopod 1.4 times longer than second pereiopod. Palm 1.2 times longer than fingers. Fingers sparsely setose; tips of fingers hooked. Carpus 1.5 times longer than palm. Merus 1.6 times longer than carpus and 2.6 times longer than ischium.

Fourth pereiopod reaching in to middle of the scaphocerite. Propodus and dactyl setose. Dactyl slightly hooked. Propodus 1.7 times longer than carpus. Merus 2.1 times longer than carpus and 2.1 times longer than ischium.

Fifth pereiopod reaching proximal end of scaphocerite. Propodus and dactyl setose. Dactyl slightly hooked. Propodus 2 times longer than carpus. Merus 2.4 times longer than carpus and 2 times longer than ischium.

Dorsal surface of pleon smooth in median region; pleura smooth, densely pitted. Each pleomere strongly setose with short hairs on posterior margin. Telson with two posteriorly directed spiniform tubercles in caudolateral corners. Protopod of uropod with single posteriorly directed spiniform tubercle on distal margin. Endopod of uropod with two posteriorly directed spiniform tubercles in middle and outer margin of mesial lobe. Exopod of uropods with transverse row of posteriorly directed diminutive spiniform tubercles ending in two bigger posteriorly directed spiniform tubercles on outer margin of mesial lobe.

Description of allotypic female. ( Fig. 2 A, 3B). Differing from the holotype in the following respects: soft uncalcified patch on palm absent; the chelae 3.0 times as long as broad, 8.7 times as long as deep; palm of chela 1.2 times longer than fingers; pleon equally broad as cephalothorax; tubercles on propodal cutting edges smaller and less prominent than in holotype; cervical groove with set of four (right side) and three (left side) anteriorly directed prominent tubercles.

Description of paratypic male. Differing from the holotype in the following respects: left chela 3.4 times as long as broad and 7.5 times as long as deep; one large tooth at about middle propodal cutting edge of left chela not so prominent; single straight spiniform tubercle on dorsal surface of ischium of left cheliped poorly developed. Cervical groove with set of four (left side) and five (right side) anteriorly directed small tubercles. Endopod of uropods without spiniform tubercles.

Remarks. The single well-developed acute and hooked spiniform tubercle in the middle of dorsolateral inner margin of carpus is characteristic for the genus Cherax . The well-developed rostal carinae and triangular shape of scaphocerite is characteristic for adult males from the subgenus Astaconephrops . Both holotype and allotype chelae were without visible damage. The paratype has a regenerated right chela, left chela 1.5 times longer than right chela; this specimen has prominent erosion with soft tissue on inner lateral side of ischium of left cheliped, right chela with indistinct tubercles on propodal and dactyl cutting edges; uncalcified patch on outer lateral margin of palm of right chela absent; the anterior part of the carapace, before cervical groove on left lateral side with large swollen ulcer.

Size. Holotype TL = 94 mm, TCL = 43 mm, PCL = 31 mm, and weight = 20.61 g; allotype female TL = 97 mm, TCL = 45 mm, PCL = 32 mm, and weight = 27.07 g; paratype TL = 78 mm, TCL = 35 mm, PCL = 26 mm, and weight = 18.09 g.

Coloration of live specimens. Background color of live individuals dark brown, marbled on sides of carapace with pale brown spots. Cervical groove and distal end of carapace orange. Pleon with prominent orange spot on both lateral sides on each pleomere. Soft distal part of caudal fan orange. Chelipeds blue with orange joints, palm of propodus blue in basal part, pale in distal part. Fingers orange, distal third black with orange tips. Row of blunt spines on inner lateral margin of palm light blue. Ventral surface of chela pale orange with bluish basal margin, fingers black in distal third with orange tips. Remaining pereiopods deep blue. Both antennal and antennular peduncle blue, flagella reddish-brown. Swollen uncalcified patch on outer lateral margin of palm pale and translucent, the rest of the margin whitish. Maxillipeds deep blue, ventral surface of cephalothorax and pleon pale.

Deposition of types. Holotype, allotype, and paratype are deposited at the Czech University of Life Sciences Prague. Holotype, No. JP2014/10-20: ♂, Indonesia, West Papua; collected by anonymous supplier of John's Aquatic wholesaler, TL 94 mm. Allotype, No. JP2014/10-21: ♀, Indonesia, West Papua; collected by anonymous supplier of John's Aquatic wholesaler, TL 97 mm. Paratype, No. JP2014/10-24: ♂, Indonesia, West Papua; collected by anonymous supplier of John's Aquatic wholesaler, TL 78 mm.

Systematic position. Cherax gherardii belongs to the subgenus Astaconephrops due to well-developed rostral carinae and triangular shape of scaphocerite (Holthuis 1949, 1950, 1982; Munasinghe et al. 2004). This subgenus includes eight Papuan species, namely: Cherax (Astaconephrops) albertisii (Nobili, 1899) , C. (A.) boesemani Lukhaup and Pekny, 2008 , C. (A.) lorentzi Roux, 1911 , C. (A.) minor Holthuis, 1996 , C. (A.) misolicus Holthuis, 1949 , C. (A.) monticola Holthuis, 1950 , C. (A.) quadricarinatus (von Martens, 1868), and C. (A.) rhynchotus Riek, 1951 . The new species, Cherax (A.) gherardii n. sp., differs from all others in the Astaconephrops subgenus in its coloration.

Cherax (A.) gherardii is morphologically most similar to C. (A.) boesemani and differs from this species in the following characters: chelae in C. (A.) boesemani are 2.3 to 2.4 times as long as broad and 5.4 times as long as deep while 2.6 to 3.4 times as long as broad and 7.1 to 8.7 times as long as deep in C. (A.) gherardii ; uncalcified patch on outer lateral margin of chelae of adult males extends from middle or distal third of opposable propodus to about middle of palm and is yellowish or pale to white in C. (A.) boesemani while it is pale, translucent and extends from about middle of palm to about one fifth of opposable propodus in C. (A.) gherardii ; in C. (A.) boesemani rostrum reaches close to the end of the ultimate antennular peduncle while reaching slightly beyond end of second segment of antennular peduncle in C. (A.) gherardii ; propodal cutting edge without large teeth in C. (A.) boesemani while there is one prominent large tooth in C. (A.) gherardii ; no setose hairy parts present on chelae except for ventral cutting edge of opposable propodus in C. (A.) boesemani while setose hairs developed in posterior ventral surface of dactyl in C. (A.) gherardii .

Cherax (A.) gherardii differs from C. (A.) albertisii in shape of chelae, and color of uncalcified patch on outer lateral margin of chelae of adult males. Chelae 5.0 to 5.8 times as long as broad in C. (A.) albertisii while 2.6 to 3.4 times in C. (A.) gherardii . Uncalcified patch red in C. (A.) albertisii while pale and translucent in C. (A.) gherardii .

Cherax (A.) gherardii differs from C. (A.) lorentzi in shape of chelae, number of rostral teeth, and color of uncalcified patch on outer lateral margin of chelae of adult males. Chelae in C. (A.) lorentzi 2.1 to 3.3 times as long as broad while 2.6 to 3.4 in C. (A.) gherardii . Each lateral margin of the rostrum with 2 teeth in C. (A.) lorentzi while with 3 teeth in C. (A.) gherardii . Uncalcified patch red in C. (A.) lorentzi while pale and translucent in C. (A.) gherardii .

Cherax (A.) gherardii differs from C. (A.) minor in shape of chelae, size of eyes, number of rostral teeth, and position of uncalcified patch on outer lateral margin of chelae of adult males. In C. (A.) minor chelae less than 2.0 times as long as broad while 2.6 to 3.4 in C. (A.) gherardii . Eyes are small and cornea is narrower than eyestalk in C. (A) minor while eyes large and cornea slightly broader than eyestalk in C. (A.) gherardii . Each rostral lateral margin bears no teeth except for 2 or 3 small subapical denticles in C. (A) minor while 3 large teeth present in distal third of rostrum in C. (A.) gherardii . Uncalcified patch extends from middle or distal third of opposable propodus to about middle of palm in C. (A.) minor while from about middle of palm to about one fifth of opposable propodus in C. (A.) gherardii .

Cherax (A.) gherardii differs from C. (A.) misolicus in shape of chelae, number of rostral teeth, and in spination on lateral carapax. Chelae of C. (A.) misolicus 2.0 to 2.4 times as long as broad while 2.6 to 3.4 in C. (A.) gherardii . Each rostral lateral margin with 2 to 3 teeth in C. (A.) misolicus while with 3 in C. (A.) gherardii . Both lateral sides of carapax with 7 to 8 tubercles in C. (A.) misolicus while 3 to 5 spiniform tubercles in C. (A.) gherardii .

Cherax (A.) gherardii differs from C. (A.) monticola in shape of chelae, number of rostral teeth, and in number, position and color of uncalcified patch of chelae in adult males. Chelae 2.3 to 2.7 times as long as broad in C. (A.) monticola while 2.6 to 3.4 times in C. (A.) gherardii . Each rostral margin with 0 to 3 small but distinct lateral teeth in C. (A) minor while with 3 large teeth in C. (A.) gherardii . In C. (A.) monticola one large whitish uncalcified patch extending from extreme anterior part of palm proper to short distance before top of opposable propodus.

Furthermore, one minor uncalcified area present in proximal half of the lower margin of palm. In C. (A.) gherardii only one pale and translucent uncalcified patch extending from about middle of palm to about one fifth of opposable propodus.

Cherax (A.) gherardii differs from C. (A.) quadricarinatus in shape of chelae, length and elevation of rostral carinae, and in color and position of uncalcified patch on outer lateral margin of chelae of adult males. Chelae slender and long in C. (A.) quadricarinatus while 2.6 to 3.4 times as long as broad in C. (A.) gherardii . Rostral carinae with strongly elevated margins reach behind end of postorbital ridges in C. (A.) quadricarinatus while rostral carinae gradually fade before postorbital ridges, margins are not so elevated in C. (A.) gherardii . Uncalcified patch consists of a red to whitish-orange membrane, extending close to tip of propodus in C. (A.) quadricarinatus while it is pale and translucent, extending from about middle of palm to about one fifth of opposable propodus in C. (A.) gherardii .

Cherax (A.) gherardii differs from C. (A.) rhynchotus in width of areola, size of eyes, number of rostral teeth, and color of uncalcified patch on outer lateral margin of chelae of adult males. Areola narrow, 4.0 to 5.0 times as long as broad in C. (A.) rhynchotus while 1.8 times as long as broad in C. (A.) gherardii . Eyes small in C. (A.) rhynchotus while large in C. (A.) gherardii . In C. (A.) rhynchotus , each rostral margin with two teeth while three in C. (A.) gherardii . Color of uncalcified patch white in C. (A.) rhynchotus while pale and translucent in C. (A.) gherardii .

Etymology. The specific name corresponds to the Latin form, singular genitive of Gherardi, in honor of Francesca Gherardi (Florence, Italy, 1955–2013), Associate Professor at the University of Florence, a brilliant astacologist and ethologist, interested in the behavior and ecology of freshwater decapod crustaceans including crayfish.

Common name. Both trade names of the new species, “Rainbow Crayfish” and “Blue Moon Crayfish,” are used for other scientifically undescribed Cherax species. The local name used by native inhabitants is "udang kuku biru" (crayfish with blue legs). Therefore we proposed a new name, Blue-Legged Crayfish, as a common name for the new species, Cherax (A.) gherardii n. sp.

Distribution. Based on information from the supplier, C. gherardii occurs in surrounding tributary streams to Ajamaru (also Ayamaru or Aiamaru) Lakes, West Papua, Indonesia (GPS S1°16'23.18" E132°12'21") ( Fig. 4 ), where also Cherax boesemani occurs ( Lukhaup and Pekny, 2008). The three connected Ajamaru Lakes are located in the west-central part of the Bird's Head Peninsula at the western extremity of West Papua on the Ajamaru limestone plateau about 250 m a.s.l. The shallow well-vegetated lakes are situated at the headwaters of the Ajamaru River which is a tributary of the Kais River. The lakes are surrounded by low and rounded hills covered with low rainforest and the gardens of the Mejprat people who live close by and in a relatively dense population ( Allen & Boeseman 1982; Bartstra 1998). A collecting trip along with a detailed survey is recommended to improve the knowledge of C. (A.) gherardii distribution.

Phylogenetics. The phylogenetic relationship inferred from two mitochondrial gene fragments (COI and 16S) results in a phylogram with a clearly defined species, C. gherardii n. sp. ( Fig. 5 ). The new species forms a strongly supported (88–100%) monophyletic clade with C. boesemani differing at 9.2% (COI+16S dataset) from each other. Cherax gherardii and C. boesemani form a sister clade to C. holthuisi and, together with C. peknyi , C. quadricarinatus , C. bicarinatus , and C. monticola , belong to the northern group of Cherax species occurring in Papua and North Australia. Cherax robustus and Euastacus spinifer (NC026214.1) here represent an outgroup. The detailed phylogenetic relationships within the northern Cherax species group are described in Bláha et al. (In Prep). From three analyzed specimens, two haplotypes were identified at COI sequence; however all three specimens share the same haplotype for 16S rRNA. In addition, patristic distance based on the COI data set among C. gherardii and the others ranges from 0.280 ( C. boesemani ) to 0.781 ( C. robustus ). These values are beyond the crustacean species level threshold of a 0.16 substitutions per site ( Lefébure et al. 2006). Both the high level of sequence divergence, along with the morphological differences described above, suggests that C. gherardii n. sp. is distinct from the closely related C. boesemani and supports the view that it can be described as a separate species.

Figures

FIGURE 1. Cherax gherardii n. sp., holotype.

FIGURE 2. Cherax gherardii n. sp.: A. lateral view of carapace; B. lateral view of antennal peduncle; C. dorsal view of right chela; D. dorsal view of carapace; E. ventral view of right chela; F. epistome and coxicerite of antennal peduncle; G. dorsal view of right scaphocerite; A from allotype, B – G from holotype.

FIGURE 3. Outer lateral margin of chela: A. holotype (adult male); B. allotype (adult female).

FIGURE 4. The Bird's Head Peninsula, West Papua, Indonesia, and the indicated locality of the Ajamaru Lakes.

FIGURE 5. Bayesian analysis consensus phylogram of selected Cherax species based on combined COI and 16 S dataset. ML bootstrap values and posterior probabilities are displayed next to each node.