Prionocrangon dofleini Balss, 1913

Kim, Jung Nyun & Chan, Tin-Yam, 2005, A revision of the genus Prionocrangon (Crustacea: Decapoda: Caridea: Crangonidae), Journal of Natural History 39 (19), pp. 1597-1625 : 1608-1612

publication ID	https://doi.org/ 10.1080/00222930400016788
persistent identifier	https://treatment.plazi.org/id/03DC87A7-FF8F-2F22-DBE0-FC09FC3729D6
treatment provided by	Felipe
scientific name	Prionocrangon dofleini Balss, 1913
status

Treatment

Prionocrangon dofleini Balss, 1913 View in CoL

( Figures 4–6 View Figure 4 View Figure 5 View Figure 6 , 11A View Figure 11 )

Prionocrangon dofleini Balss 1913, p 238 View in CoL [type locality: Sagami Bay, Japan]; 1914, p 71, Figure 42; de Man 1920, p 257 (list); Yokoya 1933, p 43; Kubo 1965, p 623,

Figure 1006; Chace 1984, p 56 (key); Miyake 1998, p 189 (list).

Prionocrangon ommatosteres: Ohta 1983, p 230 View in CoL (list) [non Wood-Mason and Alcock 1891].

Material examined

Pacific coast of central Japan. Sagami Bay, Amadai-ba, 250–450 m, 13 December 1953, 1 „ (CL 7.4 mm), 1♀ (CL 10.0 mm), NSMT-Cr R: 774. Tosa Bay, 200–250 m, 21 January 1963, coll. K. Sakai, 1♀ (CL 9.2 mm), KMNH IvR 000,013. Suruga Bay, 34 ° 46.69– 34 ° 47.59N, 138 ° 42.09– 138 ° 42.19E, 355–381 m, beam trawl, 10 June 1973, coll. Ocean Research Institute, University of Tokyo, 2 „„ (CL 4.4, 5.9 mm), 1 ovig. ♀ (CL 10.7 mm), NFU 530-2-2262 (referred to ‘‘ P. ommatosteres ’’ by Ohta 1983); 34 ° 57.19– 34 ° 57.79N, 138 ° 44.39– 138 ° 44.49E, 306–330 m, beam trawl, 12 June 1973, coll. Ocean Research Institute, University of Tokyo, 4 „„ (CL 3.4–8.1 mm), 8♀♀ (CL 5.3–9.4 mm), NFU 530-2- 2263 (referred to ‘‘ P. ommatosteres ’’ by Ohta 1983); 200–300 m, 17 December 1974, coll. H. Mukai, 1 „ (CL 4.9 mm), 1 ovig. ♀ (CL 9.9 mm), NFU 530-2-2264. Locality unknown, 1 ovig. ♀ (CL 9.8 mm), 2♀♀ (CL 9.0, 9.9 mm), KMNH IvR 000,014.

Taiwan. TAIWAN 2001, commercial trawler, stn CP 102, 24 ° 48.389N, 122 ° 7.979E, 326–331 m, 19 May 2001, 2♀♀ (CL 8.0, 9.1 mm), 1 ovig. ♀ (CL 8.2 mm), NTOUM00587; stn CP 103, 24 ° 48.839N, 122 ° 6.039E, 367–424 m, 19 May 2001, 2♀♀ (CL 9.1, 10.6 mm), 3 ovig. ♀♀ (CL 7.9–8.4 mm), NTOUM00588; stn CP 104, 24 ° 48.869N, 122 ° 5.319E, 365– 447 m, 19 May 2001, 1 „ (CL 7.4 mm), 1♀ (CL 10.0 mm), NTOUM00589 (transferred to MNHN); stn CP 108, 24 ° 48.239N, 122 ° 7.749E, 295–337 m, 20 May 2001, 3 „„ (CL 5.9– 7.4 mm), 1 ovig. ♀ (CL 7.4 mm), NTOUM00590 GoogleMaps .

Type material

Syntypes: Sagami Bay , Japan, stn 13, 350 m, mud, 1 „, coll. S. Doflein, ZSM Nr. 1218; stn 16, 400– 600 m, sandy mud, 1♀, coll. S. Doflein, ZSM Nr. 1216. Not examined .

Description

Rostrum nearly extending to tip of branchiostegal spine, 0.10–0.18 times as long as carapace ( Figure 4A View Figure 4 ). Mid-dorsal carina of carapace armed with 7–12 spines ( Figure 4A, B View Figure 4 ). Fourth and fifth abdominal somites with low median carina ( Figure 4C View Figure 4 ); sixth somite 0.45–0.54 times as long as carapace, posterior margin of posterolateral process subtruncate, lacking minute tooth but produced ventrally ( Figure 4A View Figure 4 ). Telson more or less as long as sixth abdominal somite, 0.45–0.53 times as long as carapace, posterior half strongly convergent; posterior margin rounded, armed with 5–12, mostly six, long spines but lacking median denticle ( Figure 4D, E View Figure 4 ). Eyestalks drawn out to villiform extremities ( Figure 5A View Figure 5 ), downcurved, reaching or not reaching in between antennules ( Figure 4B View Figure 4 ). Antennular peduncle with proximal segment moderately long, 0.53–0.74 times as long as carapace ( Figure 4B View Figure 4 ). Stylocerite with tip sharp and elongate ( Figure 5B View Figure 5 ). Scaphocerite more or less extending to distal margin of proximal segment of antennular peduncle, 0.47–0.56 times as long as carapace ( Figure 4B View Figure 4 ). Palm of first pereopod relatively stout, 3.70–4.55 times as long as wide ( Figure 5J, K View Figure 5 ). Dactyli of fourth and fifth pereopods short, 0.38–0.40 times as long as propodi ( Figure 5O, Q View Figure 5 ). Females with endopods and protopods of pleopods lacking lateral lobe or distal projection ( Figure 5R View Figure 5 ). In adult females (more than CL 7.4 mm), endopod of second pleopod long, about 0.67 length of exopod ( Figure 5S View Figure 5 ). Eggs about 1× 1.5 mm in diameter.

Size

Males CL 3.4–8.1 mm, females CL 5.3–10.6 mm, ovigerous females CL 7.4–10.7 mm. Distribution

Pacific coast of central Japan and Taiwan, at depths of 200–600 m ( Balss 1913, 1914; present study).

Colour in life

Body entirely greenish ivory and semi-translucent ( Figure 11A View Figure 11 ). Eggs yellowish ivory.

Variations

Of the 36 specimens examined, the variations in the number of dorsal carapace spines are: three specimens with seven spines, six with eight spines, 12 with nine spines, nine with 10 spines, four with 11 spines, and two with 12 spines. In 25 specimens still with intact telson, the number of posterior spines is: two specimens with five spines ( Figure 6E View Figure 6 ), 13 with six spines ( Figure 4E View Figure 4 ), four with seven spines, three with eight spines, one with nine spines, and one with 12 spines ( Figure 6F View Figure 6 , this specimen also with two additional subdistal dorsal spines). The two specimens from Sagami Bay (NSMT-Cr R: 774) have the telson slightly longer than the sixth abdominal somite and with a longer proximal antennular segment (0.71–0.74 carapace length). In the other specimens, the telson is slightly shorter than the sixth abdominal somite and the proximal antennular segment is somewhat shorter (0.53– 0.66 carapace length) .

Remarks

Although we did not manage to re-examine the type material of P. dofleini from the München Museum, the many topotypic specimens from Japan enable a re-description of this supposed uncommon species. All the specimens from Japan (including two from the type-locality Sagami Bay) are essentially identical and agree well with Balss’ (1913, 1914) original and subsequent descriptions of the two syntypes. Moreover, all the Japanese material in the present study bears a low but distinct median carina on the fourth abdominal somite, a character absent in congeners. To this effect, the material identified as ‘‘ P. ommatosteres ’’ by Ohta (1983) from Suruga Bay should be considered as P. dofleini . P. dofleini is indeed closely related to P. ommatosters but can be separated from it in having a low median carina on the fourth abdominal somite, the telson bearing more posterior spines, the posterolateral process of the sixth abdominal somite is ventrally produced, and the endopods and protopods of the second to fifth pleopods lack a proximolateral lobe or distoventral projection.

At present only P. dofleini of this genus is known from Japanese waters. But on the other hand, many specimens collected from a recent cruise off the north-east coast of Taiwan are found to be identical to the Japanese material, thus extending the distribution of this supposed Japanese endemic southwards to Taiwan. It is interesting that despite extensive surveys in the last 20 years on the catches of Taiwanese commercial trawlers using otter trawls, no Prionocrangon has ever been found. However, after employing a beam trawl, a collecting gear that can dig deeper in mud, to collect deep-sea benthos of Taiwan in the last few years, a number of specimens belonging to this genus were obtained. All the 14 Taiwanese P. dofleini specimens were collected from a very busy local fishing ground (i.e. the fishing ground of Tai- Shi fishing port in north-east Taiwan) further suggesting that Prionocrangon has deep burrowing habits that generally allow it to avoid the catches of otter trawls.

Kingdom	Animalia
Phylum	Arthropoda
Class	Malacostraca
Order	Decapoda
Family	Crangonidae
Genus	Prionocrangon