Microprosthema personatum, Jiang, Qiwu & Li, Xinzheng, 2014

Jiang, Qiwu & Li, Xinzheng, 2014, A new species of Microprosthema Stimpson, 1860 (Crustacea: Decapoda: Stenopodidea: Spongicolidae) from the South China Sea, Zootaxa 3784 (5), pp. 575-584 : 576-583

publication ID	https://doi.org/ 10.11646/zootaxa.3784.5.6
publication LSID	lsid:zoobank.org:pub:965915E1-8AFC-42B0-8057-1A54D0348D47
DOI	https://doi.org/10.5281/zenodo.6135325
persistent identifier	https://treatment.plazi.org/id/1E31990E-FF87-CB37-85FB-6904FAB4FCA8
treatment provided by	Plazi
scientific name	Microprosthema personatum
status	sp. nov.

Treatment

Microprosthema personatum View in CoL sp. nov.

( Figs. 1–6 View FIGURE 1 View FIGURE 2 View FIGURE 3 View FIGURE 4 View FIGURE 5 View FIGURE 6 )

Material examined. Holotype: female, MBM 109397, cl 2.0, Shi Island, Xisha Islands, South China Sea, 14 May, 1957, coll. Y. Wang.

Allotype: male, MBM 179975, cl 1.8, same data as holotype.

Description of holotype. Rostrum ( Figs. 1 View FIGURE 1 , 2 View FIGURE 2 A, B) short (about 0.5 of cl), tapering distally, broadened proximally, slightly deflexed, reaching mid-length of scaphocerite. Dorsal margin armed with 7 teeth directed anteriorly; distance from subdistal tooth to distal tip twice as long as distances between other teeth. Ventral margin with 1 small subterminal tooth, directed anteriorly. Lateral margins unarmed, proximal half strongly expanding, forming prominent supraorbital eaves, covering most portions of eyestalks in dorsal view; margin of each supraorbital eave convex.

Carapace ( Figs. 1 View FIGURE 1 , 2 View FIGURE 2 A, B) stout, covered with moderately small spines directed anteriorly. Postorbital regions armed with 3 pairs of small, stout spines; gastric region sparsely covered with several small blunt spines. Cervical groove distinct and broad; posterior margin armed with cincture of several small spines and tubercles; several small blunt spines scattered after cervical groove. Rostral base spine small, stout; inferior orbital spine absent; antennal spine strong, acuminate and curved; branchiostegal spine absent; pterygostomial spines acute; hepatic spine stout; anterolateral spines acute.

Sixth to eighth thoracic sternites ( Fig. 2 View FIGURE 2 C) unarmed. Sixth thoracic sternite with pair of narrow plates, fused posteriorly. Seventh thoracic sternite with pair of large, broad plates, fused mesially. Eighth sternite with pair of small triangular plates, rather distantly separated.

Abdominal somites ( Fig. 1 View FIGURE 1 ) unarmed. First somite short, with distinct anterior transverse carina expanding to lateral margin of pleuron. Second somite with distinct transverse groove ending at median part of pleuron. Third somite longest, with anterior transverse groove ending at median part of pleuron. Fourth to sixth somites without transverse carinae or grooves. Ventral margins of first to third pleura rounded; ventral margins of fourth to sixth pleuron subtriangular.

Telson ( Fig. 2 View FIGURE 2 D) broadly lance-shaped, about 1.5 times as long as maximum width. Dorsal surface with two symmetrically longitudinal carinae, each carina armed with row of 3 strong, acute spines and 1 small mesial subproximal spine; pair of small spines flanking each carina proximally (mesial spine less stout than lateral one). Each lateral margin of telson armed with 1 large median tooth; posterior margin rounded, armed with 3 small teeth. All spines directed posteriorly. Margin of posterior half covered with row of long, stiff setae.

Eyes ( Figs. 1 View FIGURE 1 , 2 View FIGURE 2 B, 3D) well developed, cornea darkly brownish pigmented; eyestalk stouter than cornea, armed with 3 small blunt spines anterolaterally.

Antennule ( Fig. 3 View FIGURE 3 C) with 3-segmented peduncle. Both flagella slender, subdivided, every segment with several strong setae. Distal segment of antennular peduncle unarmed; median segment armed with several lateral and mesial spines; proximal segment bearing 1 lateral spine and several mesial spines. Stylocerite blunt, curved mesially; 1 long, sharp spine under proximal segment, directed mesially.

Antenna ( Fig. 3 View FIGURE 3 A, B) stout, with peduncle 2-segmented. Flagella similar but stronger than antennular flagella. Distal segment of peduncle bearing 2 sharp spines on mesial margin and 1 distolateral spine; proximal segment armed with 2 distomesial spines. Scaphocerite semicircular; lateral margin nearly straight, slightly concave ventrally, armed with 5 strong teeth; mesial margin densely bearing row of long setae; proximal half of dorsal surface with 2 longitudinal carinae. Carpocerite short, ventral margin bearing 3 sharp spines, distolateral angle armed with 1 large spine, proximomesial angle with circular laminate lobe.

Epistome ( Fig. 3 View FIGURE 3 H) round, moderately large, armed with pair of sharp spines on each half of anterior margin. Labrum diamond-shaped, with moderately broad longitudinal carina on median part of ventral surface.

Mandible ( Fig. 3 View FIGURE 3 F, G) robust, with well-developed palp. Molar and incisor processes distinctly separated; incisor process not well developed, cutting surface without teeth; molar process stout with broad molar surface. Palp 3-segmented, distal segment oval, fringed with dense setae and with row of setae on median-ventral surface; middle segment with several setae on mesial margin; proximal segment without setae.

Maxillule ( Fig. 3 View FIGURE 3 I) dorsally concave, with slender, unsegmented endopod. Basal and coxal endites with brushlike, dense setae on distal margins. Endopod covered with several setae on mesial margin.

Maxilla ( Fig. 3 View FIGURE 3 J) with slender, unsegmented endopod. Coxal and basal endites each bilobed with dense setae on mesial margins. Scaphognathite well developed, fringed with dense setae; anterior and posterior lobes not well fused.

First maxilliped ( Fig. 3 View FIGURE 3 K) with unsegmented endopod. Basal endite large, dorsally concave, with row of dense setae on mesial margin. Coxal endite short, bilobed, with dense setae on mesial margin. Exopod long, slender, covered with tuft of setae distally.

Second maxilliped ( Fig. 3 View FIGURE 3 E) dorsally concave. Endopod 4-segmented, with rows of dense setae on mesial margin. Dactylus oval. Propodus with swollen lateral margin. Carpus short, covered with several long setae distolaterlly. Mesial margin of merus strongly compressed, forming a broad, thin lobe, covered with rows of dense setae. Exopod long, slender, bearing tuft of setae distally and several long setae on proximal part.

Third maxilliped ( Fig. 3 View FIGURE 3 L, M) with endopod 5-segmented. All segments with rows of long dense setae on mesial margins. Propodus with short brush-like setiferous organ. Carpus with distomesial angle produced. Merus with carina obliquely from proximomesial to distolateral corners on dorsal surface; lateral margin bearing 1 strong spine mesially, and another anterolaterally. Ischium armed with 1 strong, distolateral spine, and several small spines posteriorly; mesial margin armed with several spinules. Exopod well developed without setae.

First pereiopod ( Fig. 3 View FIGURE 3 O) short, slender, unarmed. Dactylus 0.14 of cl; Propodus 0.37 of cl (including fixed finger); carpus 0.49 of cl; merus 0.49 of cl; ischium 0.27 of cl. Tips of fingers and anterodorsal part of propodus covered with tufts of setae. Posteroventral part of propodus and anteroventral part of carpus covered with brushlike setiferous organ. Carpus tapering proximally; ventral part with several long setae.

Second pereiopod ( Fig. 3 View FIGURE 3 N) similar but longer than first pereiopod. Dactylus 0.20 of cl; propodus 0.55 of cl; carpus 0.93 of cl; merus 0.68 of cl; ischium 0.38 of cl. Tips of chela covered with tufts of setae.

Third pereiopod ( Fig. 4 View FIGURE 4 A–D) strongest; tip of merus over reaching tip of scaphocerite. Dactylus, 0.49 of cl; propodus 1.23 of cl, 3.40 times as long as wide; carpus 0.79 of cl; merus 0.74 of cl; ischium 0.46 of cl. Tips of chela hook-like, covered with tufts of setae; fingers slightly curved mesially. Dorsal margin of dactylus entire; cutting edge armed with 1 large triangular tooth medianly; anterior half of cutting edge sparsely covered with several short setae. Propodus with dorsal margin elevated, forming carina with row of denticles; ventral margin entire; mesial surface scattered with several tubercles; cutting edge of fixed finger armed with 1 large, round submedian tooth, bearing sparse, short setae on distal half. Carpus tapering distal-proximally; dorsal margin with row of 4 strong spines directed anteriorly; mesial surface with broad longitudinal groove; lateral surface with relative narrow and shallow groove ventrally. Merus slender; ventral margin with row of 4 strong spines waning proximally; mesial and lateral surfaces scattered with several small spines. Distodorsal angle of ischium produced, armed with 1 strong seta.

Fourth and fifth pereiopods ( Fig. 3 View FIGURE 3 P, Q) long, slender, compressed laterally, and similar in size and structure. Dactylus 0.13–0.14 of cl; propodus 0.44–0.45 of cl; carpus 0.83–0.85 of cl; merus 0.66–0.71 of cl; ischium 0.36– 0.42 of cl. Dactylus biunguiculate, compressed laterally, about 3 times as long as wide. Propodus not subdivided; ventral margin armed with about 11 movable spines. Carpus not subdivided; ventral margin bearing three movable spines (one on distoventral angle); dorsal margin covered with 2 long setae. Ischium covered with several long setae on ventral margin, and one on distodorsal angle.

Pleopod ( Fig. 1 View FIGURE 1 ) robust, without appendices; all margins covered with long setae. First pleopod uniramous, smaller than other pleopods. Second to fifth pleopods biramous with strong, oval basipod; exopod similar to endopod, 3 times as long as basipod.

Uropod ( Fig. 2 View FIGURE 2 D) slightly longer than telson, bearing rows of long setae on mesial and posterior margins. Endopod armed with 3–4 large teeth on lateral margin; distal tooth not overreaching posterior margin; dorsal surface with longitudinal median carina. Exopod with lateral margin nearly straight, bearing row of 10 teeth on posterior half; distal teeth overreaching posterior margin; dorsal surface with 2 longitudinal carinae on proximal half.

Branchial formula see Table 1.

Maxillipeds Pereiopods

I II III I II III IV V Pleurobranchs 0 0 1 1 1 1 1 1 Arthrobranchs 1 1 2 2 2 2 2 0 Podobranchs 0 1 0 0 0 0 0 0 Epipods 1 1 1 1 1 1 1 0 Exopods 1 1 1 0 0 0 0 0 Allotype. Body size smaller than female. Carapace ( Fig. 5 View FIGURE 5 A) armed with more numerous, stouter spines than in female. Lateral margin of each supraocular eave armed with 1 small median spine. Sixth to eighth thoracic sternites ( Fig. 5 View FIGURE 5 C) narrower than those of female. Sixth sternite with pair of slender plates, fused posteriorly, distal margins armed with several denticles. Seventh sternite with pair of triangular plates, distolateral angles with several small denticles. Eighth sternite with pair of plates similar to seventh sternite, but 2 plates less distantly separated than those of female. Ventral margins of pleura ( Fig. 5 View FIGURE 5 B) subtriangular, with several small denticles. Ventral surface of each abdominal somite bearing 1 large, acute median spine. Eye cornea concave medianly (probably due to preservation technique). Third pereiopod ( Fig. 6 View FIGURE 6 A–D) spinier and more robust than in female; dactylus 0.62 of cl, propodus 1.67 of cl, carpus 0.91 of cl, merus 1.03 of cl, ischium 0.46 of cl. Chela 2.33 times as long as wide; dactylus armed with denticles on dorsal margin; propodus bearing more distinct carina of teeth on dorsal margin. Pleopods ( Fig. 5 View FIGURE 5 B) narrower and shorter than those of female.

Coloration. Based on the original record, some areas of the body is covered with reddish spots.

Etymology. The specific name is from “personatus” (Latin, meaning covered with a mask), referring to its unique convex supraocular eaves, which resemble a mask worn over the anterior part of the carapace.

Type locality. Shallow waters around Shi Island, Xisha Islands, South China Sea.

Habitats. The two specimens were collected in shallow waters around Shi Island. Based on the original record, they were associated with a sponge, along with a snapping shrimp species of the genus Alpheus .

Remarks. The new species Microprosthema personatum most closely resembles the Indo-West Pacific species M. takedai and M. fujitai . The new species is unique in the genus, however, in having convex supraocular eaves. This feature is probably an adaptation to its unusual habitat. In addition, M. personatum differs from M. takedai in the following characters: (1) in females, lateral margins of abdominal somites are spineless in M. personatum , but such margins are spiny in M. takedai ; (2) scaphocerite bears fewer teeth in M. personatum than in M. takedai (5 versus more than 6); (3) propodus of third maxilliped bears fewer spines in M. personatum than in M. takedai (2 versus 3); (4) carpi of fourth and fifth pereiopods bear 3 spines ventrally in M. personatum , whereas spines are absent in M. takedai . Microprosthema personatum also differs from M. fujitai in several characters, as follows: (1) in females, lateral margins of abdominal somites are round and spineless in M. personatum , but such margins are sharp and spiny in M. fujitai ; (2) propodus of third maxilliped bears fewer spines in M. personatum than in M. fujitai (2 versus 3); (3) carpi of fourth and fifth pereiopods bear 3 spines ventrally in M. personatum , whereas no spines are present in M. fujitai ; (4) propodi of fourth and fifth pereiopods bear fewer moveable spines in M. personatum than in M. fujitai (about 12 versus about 20). In the new species M. personatum , no spines were found on the sixth somite in either male or female. Spines on the sixth somite are regarded as a variation between sexes in M. semilaeve Goy & Martin, 2013 , but are an important diagnostic character in M. fujitai Saito & Okuno, 2011 .